i drive a 1991 honda accord (172,000 miles) and when my car is idle, the engine seems like its going to die or something(except when warming it up) and when im going on the freeway at about 65 mph, car sounds like its trying to maintain speed or something because the sound reves up and down for a few seconds, then it stopps

i was told to change my fuel filter and i did, but it didnt help solve my problem, even though i really feel a good horsepower gain and my aftermarket muffler sounds louder than usual.

so could it be my oxygen censor, fuel injector, or maybe my oil pan gasket (my mechanic told me that there is a leak there)
or any other sugesstions?

 

All of my sensors, etc are good and I had a similar problem. Check your idle speed. It may just need to be adjusted. If you don't have a service manual you need one, it will tell you exactly what to do. There is a link on here somewhere to one.

 

idle speed like on the freeway?
and how will checking that help my problem?

 

what is the actual rpm at idle? or does the engine just shake. if it idles fine but shakes then you might have a bad mount. if the idle is low? then you need to adjust your idle. is there a check engine light on? if not then there is a screw on the top of the throttle body just turn it counterclockwise and you will see a world of difference.

 

clean up the throttle body,, also remove the adjuster screw, spary carb cleaner in the opening, adjust idle at 750,,
chk coolant make sure it is full, chk for any vacc leaks ,,and as asked before , is the chk engine lite on ??

 

no, its not on

 

but i might do a full engine make over, like change all the old parts and replace them with new parts, cause my car does have 172,000 miles, so its good to keep the parts new and in good running condition
i hope that eventually i will find the problem and i will also try your suggestions too, but im gonna need a lot of cash...

 

172k miles is not reaaly that much..........I got customers that have over 400k miles and never replaced the engine or done any major engine work

diagnose your problem at hand and fix it,,
Do not just toss parts in , it will ge expensive

 

sure, thanks for the advise

 

my idle rpm varies from 950 - 650, is that good?