2003 5.7gxi stalls when cold

Have a 2003 vp 5.7gxi mefi 4. When it's cold, it'll usually stall within the first couple minutes. When it does it's hard to restart, have to give some throttle and it'll start. Also while cold after revving up it'll stall when roms lower back down. Replaced plugs, wires, cap and rotor. Twin engines and other engine runs perfect. Swapped fuel pump, regulator, iac and tps. Problem does not move to other engine. Have the techmate pro scanner. Biggest thing that concerns me after comparing values with other engine is the cam sensor retard. The "bad" engine was around 67. Other engine 43 which is correct. I tried rotating the distributor but can only get it to lower to around 55. Could the distributor be off a tooth? Owned the boat about 2 years now and has been like this whole time. Engine only has about 285 hrs. Idk if someone replaced or removed the distributor previously possibly? Would the engine still run decent if the distributor was off a tooth either way? Once the boat is warmed up, it does not stall. All other readings on the techmate were pretty close to other engine. Any thoughts? Thanks!

I don't know about that particular engine but the MEFI-4 5.7l's are somewhat sensitive to the cam retard parameter (43-47 degrees). If outside of that range, GM will tell you that you'll experience "driveability concerns" - stalling being one of them.

I would check the sensor mounting to make sure it is correct...same thing with the reluctor wheel. IF they are ok, distributor position is about all that's left. The only other note I came acrosss was that the engine has to be running at 1000RPM (or a bit more) to get an accurate reading on cam retard.

I had a very similar problem, but maybe more severe, with my MEFI-4 PCM 5.7. It turned out to be the camshaft sensor, and/or TMAP sensor. I had a Crusader shop do the work because that was uncharted territory for me.

I'd suggest swapping distributors from port and starboard, but I'll assume you can't because of counter-rotating engines. If they're both same direction, that may be a good avenue to start at too.

Here's the part numbers that I used [camshaft sensor - NAPA (yes NAPA) MP143, and T Map - Mer 8M0087834]. Personally, I'd go with the camshaft sensor first. My Rinda codes totally pointed me there.

Good luck, Noel.