Ok guys, here's the deal: 1991 firebird, 305 TBI. Engine cold; fine. Engine warmed up (only once in a while does she do this); idles in cycles between something like 200 and 2500 rpms. Rebuilt motor with new sensors, this, that, and the other thing. Since it only does it when it feels like it I do not believe it is a vacuum issue. NO engine trouble codes. When I attempt to give it more fuel it increases the wavelength (rpms) of its surging. It sounds like the computer is trying to compensate for something with changing the timing (making it worse). Put in gear, the surging engine cannot handle the extra load (automatic, t/h 700-R4) and dies. My co-workers and I have lots of ideas but it would be nice to talk to someone who's experienced this issue and found the solution. I know there are already forums on this issue but no one seems to have solid answers so I thought another might do good?!