94 cutlass supreme engine problems

i dont really know too much about cars, so maybe you guys will know. i have a 94 olds cutlass supreme 3.1 v6. sometimes when i go to start it, the rpm's will jump to about 2700 and stay there for a few seconds and then drop back down to around normal. then when i go to shift into any gear it acts like it wants to stall and sometimes will. also, when im stopped at a red light, it starts to idle rough. the rpms will drop some and you can feel some engine vibration. then when you go to take off from the light, the car hesitates after pushing the gas. i havent had it looked at yet, but i wanted to see what everybody thought before i take it to a shop. i havent had a time yet where it wont start or where i cant get it started after it stalls, but i want to get it fixed. let me know what you think.

First Question: Does the 'Check Engine' light come on when this is happening? If it does, you need to get the code checked.

The first thing that comes to mind is leaky intake gaskets. If they are the original factory gaskets, they are shitty plastic and known to leak. To check these, spray some Clean-R-Carb around where the intake ports are while running. If idle changes, that's a problem.

Also possible to be Idle Air control motor/valve, this sits in throttle body and can be checked with a multimeter. Sometimes helps to take it out (2 Torx Screws) and clean ithe mating surfaces and pintle with above said cleaner. Don't get any on the IAC motor.

Hope this helps, good luck! Post what you find.

GO EAGLES!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!

well, the check engine light does come on sometimes, but i dont think it has ever come on when all this is happening. most of my commute is highway driving, but when i slow down to about 50-60 when i get off, thats when the check engine light comes on the most. but yes, it does come on sometimes when all this is happening.

oxygen sensor maybe. Check if you are getting worse gas mileage

well, my gas mileage is right around 21-22 mpg mostly highway driving. to me, that does seem a little low, but i could be wrong. ive been told by others that it could be the oxygen sensors too.

ok, so i start my car sunday night and my battery level is a little low. im thinking ok, ill check it monday when i get home from work. it wasnt too bad. well, everything went fine until the way home monday night from work. i was cruisin on the expressway doin about 80 when it kicked out of overdrive, so i slowed down and just made it off the expressway and pulled into a parking lot. the car was acting real funny. everytime i would touch the brakes, it would seem to shut off, then once i hit the gas it would come back to life. well anyways i had somebody come out and charge my battery long enough to get me home, which was only about 3 miles. i get home and at this point im almost positive its the alternator. so between my dad and myself, we get the alternator off and the new one put on($107) and that fixed the problem. in doing so, we disconnected the battery which seemed to help the problems that were going on before. i dont know for sure being that i havent driven it too much since the work was done, but hopefully this might solve the other problem. would disconnecting the battery help my other problems by resetting the computer and electronics in the car? let me know what you think!

yeah if it was the o2 sensor it would trick it by shutting off the error code for a while.