Hi all, trying to diagnose why my F134 just wasn't getting much power. I found that exhaust valve #3 was stuck open so I was only working on 3 cylinders. After looking it over, what I see is that the exhaust tappet is sticky. It isn't seized, it just doesn't move freely like the others. I poured in the Marvel Mystery oil, and ran it for about 30 miles on various trips, but it hasn't improved. So I'm undecided if I should just give it a bit more time, or pull the motor and remove/replace that tappet. Seems like a lot of work but I'm not sure what else to try. At times the tappet WILL free up, I'll be going along the highway stuck at 45-50mph, and it will suddenly surge like a turbo kicked in and I'll be doing 55-60mph just fine. Then the next time I drive, it will be stuck again. I know the spring is OK, the valve itself is fine and moving freely in the guide, it is definitely the tappet being stuck. So 2 questions: 1. Opinions, is it a lost cause, should I pull the motor? Or give it more time or try something besides Marvel Mystery Oil? 2. Does anyone really know how the tappets are fed with oil? In the FSM I don't see a picture of any oil feeding the tappets. Is it just fed from splashing oil?