Multiple people on this board have already told you how to approach this problem. Either trouble shoot the problem by addressing your ignition components (plugs/wires/coilpacks), OR do a leakdown and compression test. Forget about the crank sensor. It's not your problem.
You stated that when you punch it, you make no boost. You also say that you have never revved the new motor beyond 4K RPM. Guess what....centrifugals will not make boost below 4 K RPM.
Another possibility is that one of your cams was not degreed correctly, causing the sensation of "the car feels like it is using only half the motor". A leakdown and compression test would reveal this as well, as one bank would be totally off while the other bank would be OK.
One other thing to keep in mind that sometimes, detonation isn not audible. Numerous people have grenaded their motors due to detonation, and they never heard the pinging. Only after tearing down the motor did they notice the signs of detonation-induced damage.
Kill two birds with one stone: plugs need to be pulled one by one while doing a leakdown and compression test. As you are doing the compression test, replace the plugs. If the leakdown and compression test numbers are OK, then test drive the car and check to see if changing the plugs solved the problem. My guess is that your car is down on compression, with some existent leakdown as well.
Also, remember that you will not solve your problem until you physically address it. Typing away on this UBB will not help you out anymore than it already has. You have received advice...now put it to good use. And good luck.
1998 Ford Mustang COBRA Coupe
_______ # 21 of 5174 _______
- FMS 4.10:1 Ring & Pinion
- FMS Aluminum Driveshaft
- Stock Muffler/Dynomax Hybrid Cat-Back
Last edited by Jahel'98COBRA; 09-13-2003 at 05:11 PM.