I am now at a loss of what to do. On the way back from vacation my truck started acting up again, popping out of the carburator like mad, sputtering, just plain running horrible. I know exactly what the problem is too, an exaust pushrod and I am almost willing to bet it is on number 7 cylinder. I have had this problem before, and it seems to run good for almost a week before it bends or breaks another pushrod. Could a messed up lifter be a cause? Or could it be a flat spot on my cam that allows a slap between the rocker arm and the valve that could do it? Has anybody experienced a problem like this before?