I'd suggest two things to buy... things that will come in handy for years and multiple purposes.
1. Vacuum gauge that looks like this... you can pick one up at your local parts store for under $30
2. Engine analyzer... I have this one from Sears that has served me well, runs around $50.
This could be a fuel problem, I've had problems with the 1100 carbs
, but had much better luck with the RBS
, but it may also be a vacuum problem or a problem in the wiring...