The engines sucked in those I had 2 of those engines and use them as paperweights. If you tried tuning it, and its still doing it then its 1 of 2 things. One is it could have an air leak, or the other is its pinch could be shot(more likely the pinch).

Recommendation if you wanna run it get a HPI Nitro Star T-15 for $65 off ebay and slap that in. Its the newer version of the stock MT1 engine.

For future reference if you don't store the piston when its at the bottom of the stroke (Bottom Dead Center, BDC for short) when the sleeve shrinks from cooling off it will conform to the piston and enlarge at the top, repeadedly doing this will cause compression loss which will cause the engine to crap out.

Also alot of MT2 parts will fit on it if you run it and break something. I actually started with a MT1 and from breaking crap (the truck I got was VERY brittle from its last owner, I got a 2nd one that broke nothing yet) the truck was converted completely over to a MT2.