Connected to an Innova 5610 ScanPro, shows code P0301. Also has the lights showing red for O2 sensors, HTR, CAT and EVAP. No other code shows except P0301.

All possible causes check out fine. New wires, plugs, injectors, coil packs and camshaft sensor. Fuel pressure, compression and vacuum check out fine. Took it to a very trusted mechanic and he found the same thing everything checks out fine. Only thing he found was a slight leak down in the valves for cylinder one. Picked up a remanufactured head complete with new springs, lifters and valves. Installed with new rods and code still pops up. Also replaced the Cats, O2 sensors, Purge Valve and Solenoid Valve.

I am beyond frustrated at this point. only thing I can think of now is a wiring problem but have no idea where or how to start with that.

Does anybody have any suggestion on what might be the problem?