91 Rides Again(maybe)

I recently got my 91 grand am back after 11yrs.(my brother was borrowing)
it has a tech 4 2.5l still a great motor uses no oil. I did the tune up and injector treatments/gas treatments. It is running much better except when you put it in gear( d ) the rpms fall extremely low and occasionally dies. driving and idling its perfectly fine! this is the only problem i have left. before i start replacing sensors can anyone tell me whats going? sensors start adding up and when your buying for more than one vehicle it gets expensive FAST. Thanks, mike

Inspect air filter, try cleaning iac valve and passages, or create smaller vacuum leak to see if engine will idle better. If engine idles better with vacuum leak then iac passages are clogged. Also clean throttle body.

Thanks 3100. I did notice that when i had the breather housing off i had created a vacuum leak and it seemed to idle better. the air filter is brand new. throttle body is good to go. so when i catch a day off i will try cleaning the iac. i will report my findings. Thanks again

Success!!! the grand am purrs like a kitten. to start off i removed the hood because of the light factor and room to work. i was glad i did. I found multiple cracked vacuum lines dry-rotted and while i had things broken down i cleaned the iac and the egr. the egr was horrid and the iac wasnt really that bad but it all got cleaned. no more check engine light and idles fine in gear. time and patience played a huge factor. this wasnt a chore to be done in a bad mood or sick! hope this helps someone and thanks 3100.