Hey guys, just got a 91 RS 305 TBI (auto trans), all stock. Full tune up just done, IAC, O2 (which is new AC Delco), PCV, Coolant temp sensor, plugs, wires, new dizzy with new cap and rotor as well. Also did the fuel filter.

Runs great for the most part from what I can tell. This is my first TBI so I have a few questions. While in park is it normal for the idle to fluctuate back and forth about 25-50 rpms...sometimes even less.....it's intermittent and sometimes hardly there at all, but you can hear and feel it very slighty? Only in park, once in drive or even just sitting at a light it's all good.

Oh, my buddy and I also did a full rebuild and clean on the TBI unit itself, did all the gaskets etc...and from what we can tell there are no vacuum leaks. Tested the TPS and MAP and all seem good.

 

So I am guessing this is normal....no one has yet to respond..has to be some sort of opinion someone can give me

 

I'm wondering this as well; I have the same thing happen, but only occasionally, and to varying degrees. Sometimes it will fluctuate up to 100 or so rpm, and also does it at low rpm's in drive. In fact, at a stoplight once, it revved up just enough to overcome my light application of the brakes and pulled me very slightly forward. But it doesn't do it all the time, and usually not badly, so I'm guessing its no biggie.

 

Ya my problem is on a much lesser scale but still about the same. But I guess from the lack of response it must be normal???