GO GX 7 Port long needle

Still got a problem with the engine having an erratic tic over and revving high when coming off wot.
I have changed the con rod, seals, bearings and sealed everything up as instructed,
I have stripped down and checked again for air leaks finding bubbles coming from the front bearing area between the bearing and con rod,
the engine tunes better now and is showing the speed expected from it,
The question is should there be an air leak from this area,
the other problem I have is the constant blowing of the T3 glow plugs, I blow 2 every race meeting, I run for 7 minutes and stop the engine, when trying to restart for the next heat i find the plug blown, can not see any damage on the coil. temp when it comes in is 190
am i doing something wrong? is there another plug that is better and I should try as its getting very expensive. running on Gen2 25%