I have a 1988 Harley Davidson FLHS 1340 cc engine and I am having a big problem with it that I can't seem to solve. The motor runs great until it heats up and especially if you push it 60 or 70 miles an hour then it starts to sputter almost like it's either out of gas or as if the ignition is being shut off and you have a real problem trying to keep it running. By turning off the ignition swith seems to help but it keeps on doing it. If you pull over and shut it off it'll start back up and run fine for a short time and start doing it all over again. So far I've replaced the ignition timming sensor, I had the carburator gone through and cleaned, I've emptied the gas tank and cleaned it all out but it still does the same thing. Could I please get some help ?