I run a GRP .21 in a JAMMIN x1x buggy and a GRP .28 in a X2 truggy. The GRP.28 runs flawless, tons of power, good run time and I rarely touch the needles. My .21 has been a pain in the but. I run a fioroni turbo clutch on both and have recently went to stiffer springs on the clutch and changed from a JP3 and JP4 pipe to a dynamite 053 pipe. Helped out a bunch on the bottom end. The other problem I have had since after break in is at aprox. 1/4- 1/2 throttle it sputters like the bottom is real rich but if I lean the bottom it starts to rev like a lean bog. I have only ran GRP plugs (C5 & C4) once I hit1/2 through wide open it cleans out and runs like a s.o.b. My current needle positions are aprox. 4 1/4 on HSN and 4 3/4 on LSN. I'm stumped, my run time on these settings are parox. 11 - 11 1/2 min. My gut tells me my glow plugs are not burning properly. ANY ADVISE would be appreciated.

THANKS