Also check valve clearance, intake is 0.009 and exhaust is 0.023. Is this an ongoing issue or did it just start out of no where?Air filter? Timing? IF it has a good tune up and service I would probably do a compression test on the cylinders, could have a valve not seating, rings, head gasket, or something. Harbor freight has an inexpensive cylinder compression tested and leak down tester, might be a good idea to check both ways. Rule those out and we can go from there.
its been doing it a few years but only for about 10 seconds when it was cold then it would clear up. now it never clears up. i will get a compression tester myself and check it again. thank youThe compression is over 100 but I don't recall. Air filter is clean. How can I check the module ?