Here's what I got, 1986 951 with a LR951 Max chip, 3bar fuel regulator, an inline valve that prevents the waste gate from seeing any boost until 10psi, the waste gate has shims so that I run about 2bar of boost, 3' straight exhaust, and it has an air filter that is attached straight to the maf sensor. This is how I bought the car. Anyways, when I got it, the car was slow(1st gear)until about 3500rpm, then it took off and really produced some power 5500 and up rpms. It was like once I hit the power band, at least in 1st, I couldn't hardly get off the gas before the rpms hit 7k. Now, all of a sudden, the power starts to drop off around 6k and it feels like I need to shift then.
One day when I was driving my car, I turned it off and when I went to restart it, it wouldn't start. It start a few minutes later. Now, it won't start at all. I think its the reference sensors, so I'm going to check them. The car also didn't idle that smooth, but nothing too terrible bad. I'm not sure if these sensors would affect my top end or if the two problems are unrelated. Let me know what you guys think.

 

I think I would check your fuel regulator, the fuel pump and the DME relay. The idle problem may be un -related. Gas would cause you to drop off on the top end as well as no start.

 

I just checked out my car and I have no spark.

 

Do you know how to run that down?

 

Is the tach bouncing when you crank the car? If not, check the reference sensors and the ignition coil.