Random Misfires Cylinders 1-4

I first did the manifold tumbler flap actuator repair job and after reinstalling the manifold the engine ran extremely rough at idle and generated codes for random misfires on cylinders 1, 2, 3 and 4. I took it to my independent mechanic who said that when people attempt to repair the manifold, they typically come back with a misfiring engine because the tumblers are warped. He said that I needed a new manifold.

I purchased a new OEM manifold on-line and installed that. No change at all. It was suggested that I may not have seated the injectors properly and that I should install new seals. I purchased both lower and upper injector seals. I was able to find and replace the green seals which appear to be lower, but I have no idea where the black seals go.

I applied some engine oil to the seals and reinstall the injector rail. No difference whatsoever. Same codes for random misfires on cylinders 1-4.

I disconnected the harness plug from injector #2 on passenger side and noted a difference in the engine (hard to do as it's really running rough). Then I started disconnecting engine coils one-by-one while it was running. Really no discernible change on the passenger side, but when I got to the driver's side the engine dropped rpm when I disconnect the front and the second coil.

I'm told that the only real way to fight....err figure this out is to have it diagnose on the STAR system at a dealer. Independents don't have the STAR system and thus are generally left plugging in parts. Is this correct?

On the other hand, it would be much cheaper for me to plug in new coils with internet parts prices.

Where should I go from here?

Hate this car.