Ok, last time I'm going to inquire about this I promise. My 1991 CD turbo misfires when its given a lot of pedal. I'm very sure that it is leaning out because it never happens when I swap the upper two lines on the boost controller. So that it runs very low boost. Also that no smoke or anything visible comes out the exhaust pipe during the misfiring. It feels a lot like the power ramps off. I'm guessing losing optimal air:fuel mix, and then it just completely loses all power. For some reason it really doesn't feel like a single cylinder. I took it to a local Saab/V**** place to get it checked out just a few weeks ago. The mechanic basically took my car out and beat the [expletive deleted] out of it. And yes I paid for this service.Anyway he pulled the engine codes after getting back and it came up 2 mixture problems and a fuel injector problem. He then told me not to listen to that, it was a problem with my APC box. I have trouble beliving that because the manual boost controller I have performs exactly like the electronic. As to what the boost guage is doing during all this : It rises right on up to the checkered area of the guage and then starts bouncing back as the misfiring begins, but it will misfire its way up to the end of the checkered part of the guage where it meets the red if its floored. Anyone seen symptoms like these before? Would the fuel pressure regulator or pump be able to produce this kind of problem? Thanks in advance for any help.