I've changed the cylinder head on my 89' merc 300sel 3.0l 6 cyl line M103 engine and the engine won't start.

First, I checked the timing marks in case I have wrong timing. The mark on harmonic balancer (OIT) is off approximately 5 degrees to the small pin on timing chain cover (next to TDC sensor). ---I think it's OK.

Then, I checked if I have sparks on each cylinder using the ignition gun. Yes I have sparks on each cylinder.--- my spark plugs are working.

After that, I checked the compression in each cylinder. 1-95 2-87 3-95 4-110 5-110 6-150psi --- I got the compression.

When I checked the compression I had to remove all the spark plugs. I could see the air-gas mixture coming out of each cyl. from the spark plug holes. --- I guess I don’t have problem with the injection system because I have gas coming into the cylinder.

I have gas injection, compression and the spark! The engine should start but it doesn't

Any ideas what could be wrong????