OK guys. I'm back again. Have been dealing with a knee injury. I posted in another thread about installing a new head on said machine and the head had been redesigned with longer cooling fins on it and the blower housing would no longer clear. With the advice I got from here (making relief cuts in the blower housing and reforming it around the cooling fins) I overcame that problem. I buttoned the machine back up and cut nearly non stop for 2 hours on the mower. It only bogged and spit back 1 time (for maybe 2 seconds) and recovered on its own without even shutting off the blades. I kinda torture tested it on some grass that was pretty high and running it wide open (the customer is a teenager and father team, and i know how teenagers run equipment) but not pushing it hard enough to bog down the blades in the grass. I returned it to the customer and advised him to try it out. The owner stated that he tried to cut grass with it the other day and it repeats the same bogging/spitting back symptoms when the blades are engaged and traveling uphill. The only thing I haven't inspected/replaced ( all parts replaced needed to be replaced due to previous damage or malfunction ) is the camshaft. I adjusted the valve lash after installing the new head and the Intake and Exhaust valve both appear to be opening and have normal travel. I also replaced both pushrods and rockers that came with the head. Could the cam have enough wear on it that it's not visually evident by eye and could be the culpret? My buddy at my local repair shop says he has seen a lot of these INTEKs eat camshafts. Should I pull the engine, Crack the case and inspect the camshaft lobes next? If not, does anyone have any further suggestions on what this could be. Thanks guys for all your help.