I am having a weird cooling issue I cannot figure out. I just changed the cooling flange and changed all o-rings and valve cover gasket. Also changed the reservoir cap and thermostat. Problem is I will be driving and the temp gauge will go slightly past the halfway mark but not quite to the dash past the halfway and then go back down to right below the halfway mark. This sometimes happens 2-3 times on my trip to work. (25 min drive) I am guessing air is somehow getting into the system somehow but I can't figure out where or how. I also drilled a small 1/8" hole in the thermostat to bleed any air bubbles out that may be in the system but still slightly overheats. I have bled the system numerous times and there are no leaks. Any ideas? Car is an 01 1.8t AWM. Thanks