hey guy to make a long story short I have just pulled the 16v big port 3 rib out of a mr2 and put it in one of my ae86s so other than some brackets and water pump pulley head ache a strait drop in. I've been driving the carp out of the car and I was going down the road turning 2900 rpm and my engine light came then I had to turn and I shifted and it was gone as soon as the rpms changed. now the next day I was driving and I was tuning 3100 rpm and the light came on so sped up to 3800 rpm and it went away. I've been driving still and I am noticing as long as it is the range of the tvis opening ,if my understanding is correct 2700-3200, and held at a constant speed the light comes on any ideas?

Make sure the TPS is adjusted. If it isn't adjusted correctly this can happen. Mine 87 MR2 used to do this all the time when it hit a certain RPM, I think it was high 3s, the TPS was the issue, adjusted it and it went away.

Pretty sure the TVIS opens at like 4100 rmps or around there.