ok, i’ve been a bad jeep owner… 8 months ago my jeep (2004 liberty, 4wd, 60,000 miles) had a major tune up, oil changed, tires checked- all that good head to toe stuff. right after that, i moved to florida (from maryland) and have not had an oil change since. (i’ve been broke, and keep putting it off- and yes i know, its gonna cost more in the end but when you’re living hand to mouth, its hard) anyway, its so HOT here, so i have the AC on almost all the time. i used to get about 275 miles out of a tank of gas, but the past few months i barely get 180… and now, my transmission (automatic) with do these crazy things sometimes where it will rev when i stop, or drop so low once i stop i think the engine is about to die, etc… the engine light comes on, but then other times it will go back off on its own. what is happening? will a simple oil change fix this, or have i really screwed my poor jeep? PLEASE HELP!!
Have you checked your transmission fluid? Make sure it is at the proper level. If it is brown or has a bitter smell you need to get the fluid changed ASAP. Have you checked your oil level, as a minimum make sure it is full, but you should get it and the filter changed soon. When the check engine light is on head on over to a parts store, Advance, Pep Boys, etc they will read the codes for free. Post the codes here for advice on that.
really? awesome, i will definitely do that! i’m really scared of getting screwed by auto places saying a bunch of stuff needs to be done, because i don’t know any different to argue.
it will rev when i stop, or drop so low once i stop i think the engine is about to die, etc
That’s not about the transmission. And oil change won’t do a thing. A transmission fluid change won’t do a thing either - although I’m betting you’re long overdue.
Ask around among people that you’ve met there. Find a trustworthy locally owned auto shop. Do not go to national chain shops and do not go to dealerships. Just a small, local auto shop - the kind where the guy’s name on the sign is the same one you talk to about your car.
Take it there. Have them get you back on track for taking care of this thing.
ok… so what do you think might be causing it?
An erratic idle can often be caused by a vacuum leak or a problem with the Idle Air Control valve.
Tests for a vacuum leak can easily be done with a vacuum gauge. As to the IAC there may or may not be codes present showing a problem in that area.
Sometimes, removal of the IAC and cleaning it along with the intake passages may clear the problem up. This is all assuming the IAC or any associated electrical circuits do not have a fault.
With the CEL coming on I would think you should have a code(s) present. As mentioned, get the Jeep scanned and go from there as a starting point.
One more word of caution. You state it’s been 8 months since an oil change and have gone through a lengthy move from one state to another.
You are checking the oil level regularly aren’t you? If not, you’re begging for major league trouble.
i know… 
i really appreciate all this advice, and will get it checked asap…
Don’t “get it checked” asap. Get it changed asap. But check it before you start the Jeep again. Its way easy. Pop the hood & pull the dipstick. If its been sitting overnight or something, no need to even wipe & reinsert. Dirty & degraded oil is one thing. Running low on oil is quite another.
Not changing the oil is not likely causing your problem, but if you want to keep your Jeep, I’d change it right away before you add a failing engine to your list of woes. An oil change can be had for under $20 if you look around, less than half the price of a tank of gas. Surely if you can afford to register and insure your car, you can afford this. It will be a lot cheaper than replacing the engine.
At the risk of offending you, I would suggest that with the responsibility of owning a car, comes the added responsibility of being more aware of it’s maintenance. A basic course in checking the mechanics you can is in order. The stickers on military vehicles that I drove say it all. " The driver is responsible for checking the tire pressure, oil level, transmission fluid etc. before operating this vehicle." Paraphrasing of course.
Regardless of where you get your oil change done, before you drive away…
before you start it to drive away…
check the oil level, and check under to make sure it’s not leaking.