My car has a misfire to it. When in high gear under load the car has a violent shake to it. When this happens my wide band reads like 10:1 meaning pig rich. If I give a little more gas it runs better but is way down on power. The exhaust sounds way mellow too if that makes any difference. Just recently got the car back from a paint job. It ran very well for the first 4-5 days then all of a sudden it started running crappy.

My car has an OBDII conversion and is not setting the check engine light.

I've checked vacuum lines and they seem fine.

I've checked plug wires and they seem fine.

New cap and rotor.

Fuel pressure is a steady 40psi idle and 48psi with the regulator unhooked.

I'm getting fuel out of my tailpipes.

The misfire is not random...it seem pretty steady.

Only thing I did was change from valvoline 10w30 to royal purple 10w40. I'm going to pull my rocker covers tomorrow and pray to god my rockers all move like they should and that the oil didnt do something to my cam.

Any other ideas before I go nuts!?