weird idle, cant find answer in any other thread!

[mitsu-luver]

i have a 91 gsx, when i start the car i revs really high like 2500-3500 up and down up and down until the car gets to operating temp and it starts acting up, ill be a t a stop light and the
car will be at perfect idle, and all of a sudden itll drop untill it almost dies and somtimes dose if i let it (the oil pressure light will come on) i can now hear that it only does that when the cooling fan comes on? so i did alternator test and the alt is fine from what my autos teacher says? please help my gas mileage sucks!!

 

[TerribleTSi]

you car is old, so are the sensors. check out your ISC (idle speed control sensor, it's below the throttle body). 90% of the time that is the culprit on 1G's. also, you throttle body is probably all gross and dirty, pop her off and give it a god once through cleaning.

 

[mitsu-luver]

thanks for the help will do that tomorrow but just in case any other ideas?

 

[fwspin]

Like stated above its most likely your ISC. After replacing that if the problem continues it may be time to have that throttle body rebuilt.