I just swapped over fuel injection from a 77 z & have a high idle around 1400 rpm warm & low idle when cold around 650 rpm. There is no cold start circuit hooked up (all disconnected & blocked off) & I adjusted the idle speed screw all the way down. Could it be the water temperature sending unit or some vacuume leaks? The throttle plate does not seem to be sticking open.

Anyone out there with tips or suggestions?

I think if you have any air leaks after the air flow meter, it will affect your idle. As your car warms up, and leaks in the rubber boot from the air flow meter to the intake manifold may seal up and your idle may go back to normal. I know those boots tend to crack when they get old, it may be a good idea to replace them.

The boots look good & I re-tightened all the clamps. I will re-check for air leaks after the afm. Thanks for the reply.