XR6 Problem

[LParks]

SN#0T542224
I posted this in the Mercury forum and was told it was in the wrong place so ill try it here. I have a 2002 150 XR6. I go to launch and the motor starts right up and idles fine. I idle out to the boat lane and it gets right up on plane and runs great. Slow down and idle into a cove and fish for 30 mins to an hour. When I decide to move I pump the bulb until its hard. Motor starts right up but then idles less and less until it dies. I can put it in neutral and rev it up but when I put it in gear to idle out to the boat lane it will want to die. I have to keep giving it a little throttle to keep it from dying until I can get into the boat lane and get on plane, at which time it runs fine. Ive changed all the fuel lines, rebuilt the fuel pump, and changed the filter. Any help would be appreciated, thanks.

[EuropeanAM]

Check the thermal air valve function.

Verify good/clean spark plugs (must be the CORRECT ones, too).

If everything appears to be in order, it may be beneficial to open the idle air screws 1/8 - 1/4 turn COUNTER-Clockwise.

[LParks]

Is there a way to test the thermal air valve? And mine is loose, is that correct?

[EuropeanAM]

Thermal air valve should be snug in the cylinder head, with the nipples facing DOWN.

Valve is CLOSED when cold, and opens at approximately 100 degrees F.

One (1) nipple on the valve is intentionally left OPEN (no hose or plug on it).