this is the same question with more added 2 it. my idle is erratic in drive at a stoplight. i see the battery gage go up and down like the car wants to lose power along with the RPM gage. ive checked the battery and its good with a DMM. ive backprobed the TPS and put new vacum lines in. i have done lots of things yall. its down 2 only 2 thing that i think. IAC not ajusted right or timing issue. what yall got 4 me? if its the IAC is this thing suppose 2 be set with somthin and how? pleeeeeeeese help. 2.8 89 camaro.

 

mory,
It sounds like an IAC problem. Mine was doing the same thing a few years ago. It turns out, my IAC was compressed and full of carbon! I don't have mine with me, but a Haynes manual tells how to adjust the IAC sensor. You might check one of those out or, if yours is real bad like mine was, replace it.

I wouldn't rule out a vacuum issue. However, I believe the IAC's are a common problem with these cars (assuming yours is a TPI motor).

Hope this helps!