5.0 mercruiser

I have replaced the anti siphon valve, pickup tube, plugs, cap, rotor, and wires. The engine starts right up when cold. It struggles to get to 3k rpm. It will run there for about ten minutes the coughs spudders, then dies. Then it takes 20 minutes before it'll restart but doesn't run right.

Hi All, I've got a fault 32, calling out starboard exhaust O2 sensor- There's two on each side. Is there any way to determine from that code which one on the starboard side? Thanks, -Gerry

running take out , but 2 freeze plugs missing , still has compression though, i think it just needs a new block, engine is complete, 278hrs on mercruiser reman, bought the boat with this motor , also outdrive comes with it complete engine package, risers are 2 year old , would be a great motor...