Like Larry Bible said, this is real inmportant. I used to punish my Sears Mower w/ a Briggs & Stratton over my rocky lawn. Sure enough, I hit a root solid and the thing quit. That shear key was spent.
If the timing is off, nothing else will work right.
Others said some good stuff: tighten head down, check carb. I would do that stuff first as it doesnt take too much work. (as opposed to taking the flywheel offfirst )
'84 190E 2.3
'83 Porsche 944 (track car)
'84 Porsche 944 (parts car)
85.5 Porsche 944 (sled)