Need Help With Power Loss

My wife's sled has a problem. If I ease into throttle, it's just flat and tops out at 45 mph. If I stop and then pin the throttle, it seems to have decent bottom end then flattens out and tops out at 45 mph. Primary clutch is a brand new Comet, and I cleaned up the secondary. Also tried new plugs and wire ends. The LED on the bottom of the ecm doesn't flash or anything. I'm thinking it might be either stator or coil. How do I test? It's an expensive experiment just to buy new parts. Her uncle thinks it might fuel delivery. How many PSI should there be at the rail?
Any help anyone can offer would be greatly appreciated.