Q: P0304 code.

I've had this vehicle for three years.It has been inoperable for all but six months of that time due to a bent intake valve and jumped cam follower in the #6 cylinder. I just reinstalled the engine after a complete top end rebuild and timing set replacement (using the OTC cam timing tool set.). I spent most of yesterday trying to get it to run. It will start then rev to 2k rpm and stall when not pushing the gas. If I feather the gas while cranking I can get it to climb in rpm very slowly and roughly. During two attempts at getting the rpms up yesterday the vehicle stayed running but rough idling at 1-1.5k the longest instance was about 5-8 mins before the engine stumbled and stalled. I have replaced the plugs and wires, fuel pump,injectors, and triple checked for anything unplugged or damaged ( I even changed the intake gaskets a second time). Any advice is appreciated

My car has 112000 miles.
My car has an automatic transmission.