[FattyBoomBatty]

In order to have a good running turbo 80's car, you have to think like a turbo 80's car.

Drop that spark plug gap down. Just keep going till the problem goes away man. Or throw money at it. New coil, etc.

Also, if you haven't already, perhaps when you upgrade exhaust systems you will be smart and add a coil and spark plug in the exhaust tip for hot flame thrower action. Mayeb it won't work since you don't really have a mass air sensor, but it might!