well it's not the air mass sensor nor the o2 sensor. the shop stuck one of each in there long enough for the light to come back on. i have a 561 computer with a white label, so i'm hoping that's fine too. gas mileage is absolutely fine, exhaust isn't rich (new tail pipe is still very clean). the power curve is a bit lumpy, but i don't know if that's a volvo thing or not and it's not that lumpy, my wife doesn't notice it but i do, but it has to be on a smooth road. i did drive my mechanic's 242 and that seemed to have a smooth and solid power delivery it seemed faster too, but i have no idea what he's done to it. his was an automatic, so i couldn't really run the engine up through the full range to compare.

so what next ?

i've read here to check the fi relay, injectors, maybe the h2o temp sensor, tps.

are those all valid things to check ? is there anything else i should look at ?

and basically i'm kind of getting the sense that i shouldn't care until i get bad mileage or have to pass emissions (although i want to be a good citizen)
-mmm