Engine dies at idle speed

[TRB]

I have an 84 115ETLN which will not stay running at idle speed when either forward or reverse gear is selected. If the throttle is immediately advanced the engine will stay running and runs well all the way to WOT. However, if throttle is reduced to idle the engine soon dies. Carburetors and ignition were rebuilt. Timing and idle speed (under no load) were set to specifications. Advancing low speed timing from 5 Deg BTDC to 3 Deg helped significantly but further advance appears to offer diminishing returns. I could jack the idle speed way up but that is hard on the lower unit. Does anyone have any other suggestions that may help. Carburetor adjustments??

Tom

[boats.net]

The older an engine gets the harder to tune. Is the compression even, can you hear any rattling like piston slap, Do you notice oil spots on block at sealing area's like crankcase half, crankshaft seals, bleed hoses, etc. Make sure carbs are sync. with each other.

[TRB]

The compression seems to be even in all cylinders. I have replaced all of the hoses and do not see any evidence of leaking gaskets. I had the heads off and checked that the rings are free and that there were no deposits on the pistons or combustion chambers. I have set up the carburetor linkage as described in the manual.
However, there is one needle valve in each carburetor which, according to the manual, are a setting only and not for adjustment. I set them according to the manual and have not played with the settings. I don't know if adjusting these would make any difference in performance at idle.