OK this has me stumped. I have a 2008 Sierra 1500 Z71 w/ 65K miles. I've never had a problem and have had regular maintenance. I was on the interstate about 65 mph and suddenly the engine ran rough, it said the traction control was off and then it said service stabilitrak. I parked the truck at Starbucks, so the wife had a coffee and I turned the truck off for a while. When she was back 5 minutes later the truck ran very rough and had the same service stabilitrak and check engine light. I went to the dealer but the service dept was closed for Memorial Day. Remember this whole time the engine is running very rough and is shifting into second very hard. Trying to limp it home the truck suddenly started running correctly but still had a check engine light on. I ran the code at Auto Zone and it was P0306 a misfire on cylinder #6. The hose from the air filter to the TB was a little crooked but tight. I straitened out the hose, cleaned the throttle body and will run some injector cleaner on the next fuel up. Is there anything else I should do since I'm driving 800 miles with the family in two months. I don't think it is the coil or the spark plug since the problem fixed itself while the truck was on and moving. What do you think?