You probably have gummed up fuel lines or an air leak. It sounds like the truck sat for a while, which usually kills fuel lines. Did you use ARO? (after run oil for the uninitiated)...
Is the carb base and engine back plate sealed with silicone? I would reseal the crankcase. Check the fuel tank for cracks too...
I've got a HPI Savage monster truck with a .26 that's about to get a .28. I've actually got four nitros (three touring cars and two trucks) and one electric.
I hang out at www.rcnitrotalk.com, check in there for more help. They are a great bunch of guys...
Check out this Nitro Tuning Flow Chart, it might help...[Broken External Image]:
HTH...
Mark