Second the distinct possibility of an air leak at the intake manifold, ie the gasket. It can tear most easily in the upper right corner when replaced, I believe around the upper stud located there, but that is from memory. If it was running fine before taking on this job you will need to retrace you...

Thanks. Yes, might not be a miraculous improvement adding a rear bar. Have a strut bar also ( I realize the controversy) but hoping the combination, strut bar and rear sway will make for an improvement. Not a huge investment if I find a used rear bar, or even go for a new one from Volvo. Haven't spe...

Forgotten what people think on this subject. It's a wagon 850t with a tight suspension overall. Does handle a bit on the sloppy side when headed in to turns (feels like a boat, basically). Pros and cons to a rear sway bar, where to find one and what size should it be? How much is it likely to help w...

Check your fuel pressure, or have someone do it before going any further.

No aftermarket replacement here, OEM only for ECT.

Check engine light is not on because of a recent, or otherwise oil change. Have a shop, or parts place Autozone, etc. run the codes. Go from there. Otherwise, advice provided thus far is a starting point.

May be minor differences between 98 and earlier models. Rivet replacement is a minor pain.

"Critical speed" wobble strongly suggests tire, rim problem. Should change somewhat with rotation. Check above mentioned items, have a good tire place look. They should be able to demonstrate findings to you.

2 grand or more to do it up right. Might get lucky spending less. Assuming best quality parts, unknowns along the way, and that you will stumble across something a shop will need to help you with. Example, ticking lifters means oil pan 0 rings need replacing. Think more, be happy if you get away wit...

I actually ended up using the AC Delco unit, found one, and a pigtail, inexpensively, works fine. Search ac delco tcv and Volvo 850 it pops up. But the Pierburg (updated one) looks like a great solution as well, probably the simplest one. I wouldn't hesitate to do this simple upgrade if you suspect ...