I'm new to the volvo world and I hope you guys can help so thanks in advance.
My wagon has a slightly lumpy idle and seems to run worse during wet/humid conditions. My fuel economy is only about 180 miles around town and 220 highway. I do not have it boosted all the time either.
When its humid/wet it hesitates sometimes and once in a while when stopped it sputters (almost stalls) like there is not enough spark. When cold and dry the car still has a lumpy idle but it doesn't ever sputter and seams to accelerate much better.
I've cleaned the throttle body, IAC and grounds (soldered most of them) per the FAQ's. I have had the injectors cleaned and tested-all 'good'. I set the base idle per the FAQ. Also checked all turbo hoses for leaks and degradation.

I have also changed the following parts with brand-new parts from FCP Groton.
AMM, airbox thermostat, coolant thermostat, ecu temp sensor, knock sensor, fuel pressure regulator, distributor, coil, fuel filter, feed line to filter from pump, checked and resoldered all the 'troublesome' relays and changed the intake gasket. When I first got the car I cleaned the oil trap and hoses/y-fitting and replaced most of the vacuum lines. The car has just turned 90,000 miles, compression was 135lbs all cylinders without the throttle open. I picked it up in Los Angeles and recently moved to Omaha, NE, this is its first winter. I love this brick but I want it to run its best, so thanks for any help.

I have a few years experience with turbo cars more specifically a Buick GN which I was able to produce 12.30 quarter at 116mph and 1.8 60ft. The volvo is very similar in operation but I can't figure this out.