Just got my first Volvo home today, an 89 740 turbo wagon with 178K. It had sat for a year but I got it fired up easily and it ran fine. Has been starting and running well until today. After I got it home I pressure washed a years worth of dirt, leaves and grime and wanted to clean up the engine compartment too. I was trying to be careful and avoid the electrical stuff, so of course now the car runs like crap. It will crank fine and barely catch, chugging, sputtering and surging at idle. It seems like I may be running rich because I smell that carbon fuel odor from the exhaust. If you gas it it'll stall or stumble, slowly building up revs until it smooths out at about 3K. Seems to run ok at constant high revs but terrible at low speeds.
I tried drying off all the electrical stuff I could think of that may have been exposed to water. Nothing. I did notice that the boost needle stayed in the white at all times. At constant hi revs its well below the yellow mark and when I try pounching it and the revs start building up the needle goes near the top of the white then back down never getting into the yellow. I thought previously the needle was running in the yellow under boost but I'm not sure. Could it be related to the turbo? Any particular sensor or relay I should check? Anywhere you can suggest I look? This is my first Turbo and Volvo so I could use some guidance. Any input would be appreciated. Thanks

Dave