New to the page trying to figure out a problem with our fork lift. When starting the fork lift it run fine for about a minute as soon as you move or get up to any amount of speed it starts to misfire. I have pin pointed the misfire to cylinder 3. Are there valve adjustment to be made on these engines. This is a Mitsubishi Engine that is in the machine. Spark plugs, wire, cap and rotor have been changed. Any help would be greatly appreciated.