Hello ,
I am new to this forum, but I need help. I changed the valve copver gaskets on my 89 560 sel , bu tnow if I turn the ignition key to the on position and wait a minute tehcar make a smal combustion sound. THen it will start as it should but runns rough having no pwoer. Is it possible I have crossed my wires.

 

Sounds like that from the info you have giving.
Firing order is #1 5 4 8 6 3 7 2, cylinder 1 2 3 4 should be on the passenger side I believe.