I have a 1992 Camaro RS with the 305 in it. To help try and solve this, I'm going to post all that's going on with it, since I believe the problems are connected. On startup if the car hasn't ran in about 4 hours, the engine will constantly go down to about 500 rpm then rev itself up to about 1500 rpm. It'll do this for about 20 min (not the exact same every time, 20 is average) then it will steady itself out. If I rev the engine in park and in neutral, it performs perfectly fine. The moment I put it into gear, the engine will bog down real bad and have almost no power to it. Here's the weird part. If I push down on both of the window buttons (does not matter up or down, or if the windows even move) the engine immediately picks back up as if nothing was wrong at all. Though this can only last for a short bit before I have to let go to what I can only assume is to recharge something with the buttons. I can do this every minute or so. I believe it's some kind of electrical mismanagement. I've changed the spark plugs, the fuel injectors (throttle body), and the throttle position sensor. all no luck.