Please help! I have a 2008 Mitsubishi Endeavor with 308,000 miles on it and am on the return portion of a road trip with 700 miles to go and my car is driving terribly. I had my oil changed today and they used a high mileage oil, said that my filters were fine and I needed to do a tranny and power steering flush which I said I would do once I got home. My service engine soon light has been on and every so often while idling or slowing down my car would putter and act as if it would bail out but never actually die. When I ran the computer it said it was an issue with the o2 sensor but after put a fuel cleaner in the system, it always felt better. Not today 
I drove about 900 miles Saturday, did a little bit of in town driving Sunday and it started to putter while idling but what was new was the surging during acceleration and the continual puttering or bumpy ride feeling when I’m at high speeds and 2000 - 3000 rpms. I’m in the middle of nowhere and after talking to Autozone, my mechanics and trying to self diagnosis online, I’ve been told that I need to indure the bumpy ride to get home but when I do, will need to figure out what with the o2 sensor needs fixing or Ill need new spark plugs or a new fuel pump. all that sounds good but the way my car is puttering feels terrible! there’s no odor, leaks or sound … it just feels like I’m going 80 miles an hour but I’m going to stall out at the same time. what is your opinion on my situation? I honestly don’t know how close I am to anything if I need to do something right now and I’m getting short on time
When was the last time the spark plugs were replaced?
When was the fuel filter replaced last?
Please post the exact fault code . . . eg. P0130, P0135, etc.
If your idle is rough, I’d first clean the throttle body and idle air control valve, if you have one
Are there any obvious vacuum leaks (hissing) at idle?
Has anybody hooked up a fuel pressure gauge?
my mom had this car before me but I’m pretty sure there hasn’t been any new anything other than the AC condenser. I don’t have the code with me Bc I actually had that done a few months ago. No leaks, not been hooked up to anything
You car is running very poorly and that can be for any number of reasons. Air, fuel, spark, compression. So as db4690 noted, knowing the codes might help, the age / mileage on the plugs would be relevant info, and whether or not anyone has checked for vacuum leaks or evaluated fuel pressure. If its running poorly even when flat out at 80 then you’re probably looking at fuel delivery or spark.
No one can tell you whether or not you’ll make it home. If you were my kid or wife or something, I would say to take the car to a local, independent garage and stay put until it’s running better.
So far, what you have told use is equivalent to going to the doctor and saying “I don’t feel well. What’s wrong? And will I be ok to go on my business trip?”
Does the Service Engine Soon light flash when the engine starts to “putter”?
I’m sorry I don’t have any codes for you and I know that it’s either going to be the fuel pump the o2 compressor or spark plugs but when I mostly worried about is if it is any of those things am i OK to drive this car or am I going to blow something up?
the check engine light has been on ever since I ran the computer at autozone that’s when it said something about the o2 sensor but I haven’t had it looked atbecause whenever I put a fuel cleaner in the system it would feel better
Well, I’m sticking with “who knows” if you can drive it. If the check engine light is flashing then you do stand a good chance of doing real damage. Even if it’s just bad plugs, that is also doing damage to the catalytic converter.
And so I’m sticking by the idea that you should stay put and have a shop look at it and find out what it wrong.
You’re in the position right now of:
Taking it to a shop for a proper diagnosis and at least a tolerable, short term repair.
Selling the car off as salvage based on the miles and buying a plane ticket home.
Motoring on with a wing and a prayer in hopes you will make it.
Seven hundred miles is a long ways to push a car that is struggling and pushing often leads to even more problems.
Sorry I can’t be of help but there are just too many possibilities without some kind of light diagnosis to start with.
Wild guessing, I might take a stab at a failing fuel pump if it’s the original and the filter has never been changed.
The closest thing it sounds to me like it may be is an ignition coil causing a misfire; this model has a coil on top of each plug. That’s why I asked about the SES light flashing.
However, as those above me (most with more mechanical expertise than me) have suggested, with as little information as we have, it’s not really possible to tell you if it will hurt anything to drive it home.
Thx guys. Wish me luck
I’m a little unclear on your situation. If you can get to a nearby mechanic and you can afford a repair, that’s the best thing to do here. As others have said, definitely don’t drive it if the check-engine light is flashing, as that means that damage is probably being done.
I guess you know this now, but I have to point out that setting out on a long trip with a car whose check-engine light is on isn’t a good idea. In addition to the chance of breaking down, you might have used more gas than necessary for the trip.
Ya know what I don’t know, when was the air filter, gas filter trans filter, spark plugs last replaced, maybe even the serpentine belt or timing belt if applicable. You are I am sorry to say someone who thinks of maintenance of cars as an option, until it does not work, and then you through your hands up in the air going why?
I agree, a thorough tune-up might be all you need. If you don’t know when the plugs were replaced, replace 'em. Same with the air filter and fuel filter. Clean anything you can spray carb cleaner on.
found a place that was open and they replaced my spark plugs but it ended up being a bad coil that still isn’t fixed so I’m on the road and know what I need. TY all
So, she found out the coil was bad and decided to make a 700 mile trip without getting it replaced. If I had any hair left i would tear some of it out!
Well the US is big. What state are/were u in? Maybe u were in Idaho and driving to Denver? Or fla and going to Atlanta. Lots of shops between A-B.
“she found out the coil was bad and decided to make a 700 mile trip without getting it replaced. If I had any hair left i would tear some of it out!”
+1 to Oldtimer’s comment.
Even if replacing the bad coil might have been somewhat more expensive in the OP’s unknown remote location, I think that it would have been a good investment in order to have a bit more assurance of being able to complete her trip w/o a breakdown.
Now, by continuing to drive with an apparent engine misfire, she will undoubtedly have to replace the catalytic converters and…God only knows…what else. Any way I look at her decision, I see false economy, and I recommend just junking the vehicle for its salvage value, rather than spending any more money to fix this 300k+ mile abused vehicle.
The Charge of The Light Brigade…
Yes, it sounded like a bad ignition coil.
I don’t understand why it was not tested before the spark plugs were changed, and I also don’t understand why it wasn’t changed, unless it wasn’t available in that area. The labor cost should have been next to nothing extra, as they had to remove the coils to change the spark plugs.
All I can say is I’m relieved that I’m not riding in that car.