Check that the engine has the injection pump on the right stroke. These cars can run much better than the old 123s with the injection pump on the wrong stroke. You mention a lot of carbon and that makes me suspicious.

Basically with cams in proper position. The tang in the injection pump should be about center when you move the crank to the right degrees for start of injection. The smallest distance as possible turned with the crank to get there. We had a member purchase a car and drive a long way home.

His engine not running right was exactly this. You may have also gotten he injection pump on the wrong stroke when you had the head off. You did make sure both the harmonic balancer marks and the cam marks where lined up when you pulled the head? If not there is a fifty fifty chance of it being wrong right there.

It does happen. Just by neglecting to check the cam marks are lined up when the bottom harmonic balancers are. Or else the injection pump was not on the right stroke when you purchased the car. You then duplicated it when you did the head job.

Anyways you have to stop playing around with the timing marks until you verify the injection pump is on the right stroke.

It only takes a few minutes to check and is absolutly required in your case.