[Mike Taylor 3601]

Art,
If ignition,fuel OK, I would check for valve leakage w/ rockers removed and header,use shop air full pressure and cover intake and ex ports w/hand to feel for leakage,this will show problems that a normal leak down or compression test will not show.
We have even went as far as spraying soap in runners to find valve leaks,it sounds like overkill,but I have found LOTS of guys problems that way after they have changed every thing in ign.and fuel system and have ran out of parts to change and gave up,when they had valve leaking slightly.
A compression issue will cause rich cylinder.
Another ideal is if computer had problem causing injector to spray too much or wrong time.
Have seen computer cause one injector to act up.
Could've damaged lifter if lost oil to lifter during oil filter problem