dezerttoyota

Ive been having a missfire on my 22re over the last wee and need help figuring it out. I replaced the head valves and cam about 3 months ago and after the truck ran perfect but when I went to smog it, it failed horribly due to being rich. So I cleaned they air filter(which is a k&n) and changed the cat and put some fuel system cleaner in the tank. This worked and it passed smog. The next day I started noticing a missfire around 2000 rpm. So I put plugs wires and cap on it with no change. I cleaned the afm and no change. ThenI cleaned the injectors and changed thefuel ffilter and no change. I read on here about reducing egr gasket hole so I tryed that and no luck. Any tips on what it could be?