When I purchased my 08 450 recently it ran begrudgingly. I had charged the battery, changed the oil, spark plug (original was black), and fixed a broken wire to the tps sensor, it would run with a lot of backfiring. Fast forward, changed the tps sensor (set to .62), fuel injector, water temp sensor, air filter, tip over sensor with eliminator, Dynatek coil/wire, and battery. Compression is a hair over 50lbs cold. I did check the timing and valve clearance, the exhaust was in spec (decomp spring is present) but the intake was at .4mm. It is now back to spec between .1 and .12mm, which it will no longer run at all. How does the large intake valve clearance relate? I have a programable ecu on the way and am leaning towards rebuilding the top end to see what's in there. The exhaust is aftermarket slip on and welded together so there is no checking the packing. I did try a Dynatek FS controller but the error light came on so I removed it. It makes me nervous after reading about a problem with the same unit. Any suggestions would greatly be appreciated.