Hi, I am posting this because I am completely stumped.

I had to replace a head gasket on the driver side, but went ahead and pulled them both and had them done over at a machine shop. I reinstalled them, following standard procedure, and buttoned it up, connecting everything (I was careful about marking every hose and wire, and nothing is hanging loose).

It seems to idle fine, but when driving, it essentially won't go above 2500 RPMs. It almost seems as if there is no advance.

I know the timing is correct - I have since pulled off the timing cover and the camshaft marks line up when at TDC. I seem to have spark all around - I have replaced the spark plug wires and even hooked up an analog induction timing gun and cylinder 1 and 2 are firing.

Strangely, OBDII says 'random misfires' and misfires in 2, 4, and 6, which really has me confused. I put a dowel on injector 2 and it sounds like a normal injector.

Is this consistent with any kind of sensor failure? It worked fine until the head gasket failure. But it did sit a while - I got injured right after pulling it apart and it sat 8 months. But I can't understand what would have changed over that period in terms of the electronics.

Could it be the gas? Could the machine shop have mixed up the cam gearing? As far as I can tell it only fits together one way. Otherwise I am stumped.