My original head had a burned valve horrible idle whole car shook hard to start horrible sputter on acceleration cyl 1 and 3 was at 180psi cyl 2 at 120 and cyl 4 and 30 burned valve was on cylinder 4 side Ofcourse changed head got a little better idle, acceleration is not horrible as it used to be but CEL is still on and blinks while acceleration or idling (misfiring) it sputters a lot I can hear it I changed the spark plugs again with the new head and idle got better by a lot acceleration like I said got a lil better easier to start up starts up way faster I haven’t changed the spark plug wires tho but they are fairly new I bought them a month ago. Maybe misfire ruined the plugs too? Idk. I tried unplugging fuel injector and wire on all cylinders the engine changed except cyl 4 it stayed the same like it always did. What else could it be? Firing order? Dizzy timing? Cuz I threw my old dizzy on the new head so idek if it’s timed right. New timing belt water pump tensioner installed at TDC HELP

Check mechanical timing, check ignition timing.

Check compression and and do a leak down test as well.

It’s cheap enough to replace the plugs if they are fouled.

Check the CEL and what codes are popping up.

CEL codes are cylinder 2,3,4 are misfiring compression with the old head with burned valve was 180 120 180 30. I’ll do another one with new head. Mechanical timing is good I think cuz I installed a new timing belt and everything was lined up at TDC. I think my ignition timing has to be set because I had to remove the distributor from my old head to my new head and I basically just bolted it on so it may be off. I’ll also try the leak down