This one has me confussed, the engine is a brand new long block 3.4l push rod, new vacuum lines (stainless steal from RD) with new rubber grommets (no signs of vacuum leaks with the carb clean test).

Car idles at about 1100-1200 rpms in nuetral/park when it's cold (~0-25* each morning this last week), very smooth, no hunting/bouncing. Cold or hot the car purrs like a kitten at 900 rpms when in gear (with and with out the breaks applied). The problem is when the car is hot and in nuetral or park, the idle will start out a bit high like ~1200, then it'll dip to ~900, then surge to ~1400, then dip to ~500 and back and forth then back to the ~1200 for a few seconds. The car will usually stall at some point in time doing this. But if I throw it back into drive or reverse the idle will go right back to 900 rpms and sit there.

Any ideas?

What size and what kind of injectors did you install?

sorry, I forgot to mention that. #19 disc injectors. I've heard that they can cause idle hunting due to their faster response times, but since the engine idles fine when cold and while in gear, I figured they would be a less likely culprit.

-Rick

quote Originally posted by ThatRickGuy: sorry, I forgot to mention that. #19 disc injectors. I've heard that they can cause idle hunting due to their faster response times, but since the engine idles fine when cold and while in gear, I figured they would be a less likely culprit. -Rick

When it's cold, it needs a richer mixture (more fuel). When it's in gear, the IAC will attempt to maintain idle speed, giving it more air. This could compensate if the injectors are flowing too much.

I'm not saying that's what's going on. Just something to think about.
Mine has 19 lb. pintle type injectors and it hunts once in a while, but not too frequently. If I rev it up once, or pull it into gear, it settles down.