1984 mercruiser rebuild with ignition problems.

[rolmops]

I rebuilt my 3 liter 140 Mercruiser and also my Islander. Overall although less than perfect it looks fine. One thing has not changed. I cannot get this engine to go over 3000 rpm and although it starts up fine, after 5 or 10 minutes of running,even at only 1500 rpm suddenly the rpm gauge goes bunkers and the engine runs very irregular and then shuts off. 10 minutes later I can start it up again and it will run fine (but not at WOT) for a few minutes and then it shuts of again.
This engine has a Michiganmotorz Delco ignition module. Can it be that this module overheats? What to do about this?
Thank you,Cornelis

 

[rolmops]

I just replaced the alternator ,the coil and the distributor. Now everything runs smooth and almost as it should be. It makes it up to 3200 rpm which is still a long way from 4500.
I set the timing with a shunt at -1 ,but when I remove the shunt the timing reads 18 which is way above the 12 degrees which is used with regular points.
Does the Delco ignition module use a different timing number or am I just doing things wrong? I do not want to melt the pistons because of too early ignition.
As always,thank you for your advice and opinions