What are your plugs gapped at? If it feels like it stops making power around 3800 (when the boost is starting to build-up) you easily could be blowing out the spark. I've seen it many times.
Try a .040" gap or even .035" to solve the problem. It's a quick and cheap thing to check before you spend alot of money elsewhere.
The scanner is a good idea as well.
Take it easy,
E
__________________
1991 5.0 LX Coupe - 40,750 miles
331 cu. in. / Tremec 3550 / BFG Drag Radials
12.22 @ 114.31 mph - w/1.89 60'
|