So after installing a new head (had new valves & guides installed) Ive been battling a horrible missfire. Infact its bad enough it caused the intake rockers (one from the #2&#3 cyl) to be knocked off. The following are everything Ive tried

Pinched off fuel return line- no difference
Replaced plugs- no difference
Installed Spooling Up COP- no difference
Gaped plugs all the way from .015 to .030- no difference


The symptoms remain the same

1) Stumbles horrible when I try to rev it
2) Horrible rough idle
3) Only seem's "OK'ish" under boost
4) Dies if I dont feather the throttle

My Engine codes Im pulling off the ECU are as follows
P0335 Crank pos sensor (sensor is less than 3K miles old
P0122 Throttle pos sens circ low
P2228 Barometric pressure low
P0500 Vehicle Speed sens error

HELP!!!!

 

I suggest the possibility that valves are are sticking open. Then, when they close with the help of the piston (ouch!), the rocker gets popped off. This might be due to binding guides, binding springs or too much rpm. I think the electrical stuff is maybe a separate problem.