If you are getting air bubbles it is an air leak. Check some of the things others have said. There is no need to get it pinched. That is NOT your problem. I have a v-spec with just about no pinch and it still runs great. You might want to try a new tank and fuel lines. That is an easy and fairly cheap way to insure it is not in the fuel system. It is a good Idea to replace these items fairly often anyway. I would also get some different sealant. I use racers edge carb sealant. If it ran well right after you sealed it up and started running eratically after awhile it is likely that the sealant you used was not fuel safe and dissolved. I would also reccomend setting the carb needles back to factory settings and restart from there. Also change the glowplug to be sure.