Mercruiser rough idle and stall

[BombBird21]

Need some help I have a 2003 merc 5.0 mpi and it runs fine in gear but at idle is rough and eventually stalls out. Changed the idle control valve and nothing changed, if I tap on the ecm with a screw driver it runs fine for a while. Does this mean the ecm is bad?

 

[alldodge]

if I tap on the ecm with a screw driver it runs fine for a while. Does this mean the ecm is bad?

Probably not, more likely it has a bad ground/connection

Remove the connectors and grounds and see if they need cleaning

 

[BombBird21]

I will try that tomorrow. Thanks.