Mercury Laser 220 XRI EFI. Lacks power and runs uneven/missing.

[Tobias]

I'm still fighting my 220hp Merc and I feel like I'm tried every trick in my book with no success.

So far the following things been done:

New sparkplugs
Watersprayed ignition components
Ohm tested sparkplug wires
Put on extra ground cable to the ECU
Checked for corroded ground cables
Got the injectors tested, none is leeking or clogged
Cleaned throttlebodys and housing
Cleaned all fuel filters
Compression test
Checked vaacuum hoses

Well, I think that is all, I don't know how to proceed in the troubleshooting. It still runs uneven with a fluctuating tachometer.

How should I proceed? All input is welcome since I'm really on my own in this since there isn't a outboard mechanic that got a clue about these engines in Gotheburg, Sweden..

Please help me guys.

[Tobias]

[Tobias]

I found this green wire and it is not conected anywere, don't know if it is suppose to since I can not find any male contact for it either.

[Tobias]

I found this marking at the powerhead, I guess the powerhead has been replaced over the years.

[Merc 2.5]

Need do a spark test, can get cheap spark tester at most auto parts, if nothin shows up there ,put a timin light on ea cyl and c if ur losing fire (if it will start)