There's no reason why your engine shouldn't perform like any other. Don't risk losing a plane to an unreliable engine. Remove the pump etc. and follow some simple steps:

1. RTFM (read the manual) for your engine. Use recommended fuel and break in procedure. Google for tuning tips, there's plenty. Read till your eyes bleed and read more. Use an engine test stand if possible.

2. Thoroughly check, clean, and test the fuel system. Ensure no clogs, clunk is working right, muff press line has no leaks, filter clear, fill line if installed is closed, oil buildup in tank, etc. Test for good flow by blowing in press line. Check carb for clogged idle air bleed etc.

3. Use new glow plug and new fuel - shaken well to mix before fueling. Stale old settled fuel even a month old can cause problems.

Good luck and happy flying.