Surging Idle problem. 6.2l sea ray 01.

[Oldnbold]

S/N 0M065176 This is my 1st full season with this 01 6.2l with 530 hrs current. Ive put about 40 hrs on boat.
Problem: the boat has a surging idle when in neutral and cold that is progressively getting worse. In reverse the engine wants to die And usually does every time I back out of my slip. Extensive warming to bring temps up to open the 10 hr old thermostat and engine dies every single time. Engine fires right up afterward. boat runs fine on plane and while slow cruising at 1k RPMs. I’m not smelling a rich exhaust condition
Where do I start to troubleshoot this problem?

 

[alldodge]

Thanks for the serial number
Best way to find out what is going on is with a scanner. Need to see what the MAP, IAC and TPS are doing. Once it warms up I would think the MAP and/or IAC

Connect digital voltmeter to the MAP and IAC at idle to see what your getting

Ensure your fuel pressure is at 43 psi