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.

[Onetime]

Might want to post in Tech section instead of Buy and Sell. Probably get better response.

[86shadow]

I had one drive me crazy until I found bad plug on bottom injector. I think this is not unusual because it collects moisture when it sits for a while. Hope this helps.