Cutting out

This may seem stupid,but have you checked all you grounds? Sometimes we forget to put back the chassis ground staps when swapping heads etc. If I remember correctly,there is also a ground for the engine controls by the thermostat housing which seems to corrode readily.Whenyou changed the IAC,did you clean out the cavity it threads into? Generally if it doesn't toss a code,it's not in the engine control system. Pull the distibuter cap,,are the posts all corroded,and a bunch of trash laying all over inside? Just a few things I've encountered.

Thanks for that Halftanked, I've replaced the dizzy and all it's internals, but I'll check all the earths after breakfast:)