92, 172000. About every other time when starting the truck it will crank over just fine but when it fires the motor has a hard time running at first and after about ten seconds it seems to catch up and run perfect. The sound is kind of hollow like low compression during those first ten second. The other times it starts and runs like normal. I've checked for vacuum leaks with no luck. Ran injector cleaner and switched to premium fuel with no change. Any ideas?