Update:
Just checked Compression. Every cylinder had 8bar equally (about 116PSI). Don't know what it's suppose to have, but 8 bar sound pretty good for a 4 Cylinder natural aspirated.
Compression was build up and released with every turn.

 

Come on folks, please. Somebody must have an idea what the problem is. This car drives me nuts, but I'm not giving up.

Yesterday I took the cylinder head cover off and cranked the motor by hand to see how the timing is doing.
I thought I found the problem while turning the motor and seeing a firing order of 1-3-4-2.
I thought Yesssssssssssssssss. No engineer will do this order. I expected 1-3-2-4.
Yah, no. 1-3-4-2 is correct. Aaaaaaaaaaaaaaah.
Ok, I thought, I should take the timing cover off to make sure the dots are aligned, because if the chain jumped just one tooth over I probably won't see it when cranking the motor by hand.

Double checked the Haynes book. Sorry guys, but the Chevy engineers must've been out of their minds when they planned that motor. You have to take pretty much everything off the motor below the cylinder head to be able to remove that cover.
V-Belt, tensioner, alternator, water pump, power steering pump, AC Compressor, Starter, Motor mount, exhaust, oil pan. Are you kidding me?