i just got my rxy7 done. its a 87 se with turbo2 everything in it. it ran perfect in my other car. i bought another rx7 that was in perfect condition as a roller. im thinking it might be the inner cooler piping. when i had the same setup on my last rx7 it was doing it. how could i check all the piping to see where the leak is? but another thing wouldnt it do it at high boost? mine runs perfect the more boost. it seems like b4 it builds boost it runs like crap. then after boost it doesnt miss a beat. is there a way i can test it? i tried carburator cleaner and never heard it idle up.

 

Maybe try a lighter or flame by the elbows of the piping to see if it is blown out or sucked in anywhere along it? This would tell you of a leak, but would be hard to do sitting there. Or you could try taping the joints with aluminum tape to see if that helps?