I posted here a year and a half ago about a 502EFI problem. I received some really good advice that led directly to solving the problem. I had a ruptured diaphragm in belt driven fuel pump. I had it fixed and my boat ran great for 2-3 months before I winterized. This year when I lowered boat into water for first time I started both engines. Both fired virtually immediately. I noticed a little irregular idle on starboard engine. This is same engine I had problem with last year. I decided to pull out of my slip and when I put both both drives in reverse the starboard engine stuttered and finally died. It started back up immediately but would not idle in gear. I finally got out of no wake zone and got boat on plane with no problem. Running about 3200 RPM the starboard engine tach hit zero just for an instant then came back up to 3200. It did have the tach stutter a couple of more times and I headed back in. Still no in gear idle. Idling along on port engine. I started starboard engine and revved it just a little and tach didn't come back down immediately as it should. It did come down but not quickly as it should. My initial thought was that when I re-installed all 4 batteries I somehow left a wire off somewhere. I opened the hatch last Saturday and searched for a loose wire laying somewhere that I really hoped I had missed.I could not find a loose wire anywhere. Because of the instant tach dropout my gut feeling was that it is something electrical.

I will appreciate any advice and thanks in advance for the help here.

Just a guess, distributor module