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Why is my car hesitating while I drive?

My 2000 Oldsmobile Intrigue (Automatic) has 142,000 miles on it. Our car has been hesitating when I drive on occasion. It does it randomly, it was once or twice a month, now it’s about 3 or 4 times a week. I can be either trying to accelerate from a stop or already going 50 and trying to speed up to 65 or something and it won’t go. The RPM gauge will fly up to 3500 and my MPH gauge will not move. When it does this the “Check Engine Soon” light flashes, but as soon as the episode is over, shuts off. It does it anytime of day, whether it’s the first time started for the day, or been running for hours. In recent months we’ve replaced the battery, the starter, the timing belt, recently the fuel pump as well as a few O rings. We are tired of fixing this car and not having this problem taken care of. Our mechanic can’t seem to find anything else wrong. Can anyone on here give me a few ideas?

Is it a really “Check Engine Soon” or is it “Check Engine Light”

If it is a CEL (Check Engine Light) it should be storing an error code.

 That CEL (Check Engine Light) is just a kid in class waving her hand trying to get you attention because she has the answer. You need to have the codes read. Some places will read them for FREE. Try Autozone or Advanced Auto Parts. Get the exact code (like P0123) not just their translation into English and post it back here. 

I am not sure what exact system you have on your car.

it is a Check Engine Soon and we’ve tried pulling codes, the only code it gave us was the fuel pump, which we replaced :frowning:

It could be something like a clogged fuel filter or the fuel pressure being wrong. Was the work done by a mechanic? He should have replaced the filter and made sure the pressure was all set.

For a change, I am going to disagree with Remco.
If the RPMs are shooting up, but the car does not increase its speed, my first thought would be that the transmission is slipping. A fuel delivery problem would not normally be associated with higher RPMs.

First, check the transmission dipstick in order to determine the level, color, and odor of the trans fluid.
It should be red and should not have a burnt odor.

If the fluid is red in color, but the level is low, replenish it with the correct spec fluid, as noted in the Owner’s Manual.

If the fluid is brown or black, and/or has a burnt odor, you are probably looking at evidence of the need for a rebuilt transmission.

Please check the trans fluid and then report back to us–in this same thread, rather than starting a new thread.

Yeah, that could be too.
Let’s face it: it could be a bunch of different things - a virtual smorgesbrot of different causes, if you will.

Since they replaced the pump, I was thinking that the hesitation issue could still point to a fuel issue.

i would check for a leaking break booster or a vacuum leak will cause a hesataton

jsims was right. they finally figured it out and replaced it. I had a vacuum leak. Thank you everyone :slight_smile: