If you have plenty of pinch yet when you turn the fly wheel by hand you might just have a tuning issue and the engine is to rich. I would put it up on a block and try to get the engine to heat up with the glow plug starter on the engine when it is running and tune it. What size is the engine and what temp is the glow plug. If it is a big block engine you can run a medium plug or if it is a .18 engine run a hot plug. I have seen a glow plug that was working when I put it on a glow starter but when I tried to run it on the engine it would just die when I took off the starter.