Makerbot still failing

I tried the Thing-o-Matic again. 5 perfect layers, then suddenly skipping, only thin, uneven streams filament dripping out every now and then and jut utter chaos. I'll clean nozzle and PTFE-tube with acetone for 4 days. Then try again. I suspect my PTFE-tube to be too wide for this filament. As the print progresses the heat travels up and the filament widenes as there is room for it to widen. Will try again on tuesday night.