I actually have the same problem with my 98' S70 T5. I just did a compression test on it yielding the following results when dry:
Cylinder 1: 170
Cylinder 2: 160
Cylinder 3: 170
Cylinder 4: 160
Cylinder 5: 180

Cylinder 5 (wet): 200

Any suggestions? Is there a fix, or is the volvo DOOMED?!

 

I was hoping you guys had figured something out that I hadn't. My wife's car had this problem on 3 different cylinders last week. Before that, it had recorded misfires on ALL the cylinders. We could barely get back from the airport parking lot with the car in this condition. This all began after we parked it for a week at the airport. Driving back from the airport the car died (stalled) 3 times with the CEL coming on. Later checking with the ODBII unit would show misfire codes galore.

I took it to a Volvo specialist who charged me $100 to check out the car and concluded that nothing was wrong with it. The couldn't reproduce the problem. I hate it when that happens. After much complaining, they dropped the diagnostic charge to $52 and reset the codes. Whopee - I could have done that myself. They had no suggestions regarding how to fix it. Well sure enough, about 3 days later the misfire happens again and the CEL comes on.

Now, I have replaced the wires, rotor and cap only about 1.5 years ago. I used OEM stuff from FPGroton. They look fine right now. So,I figured maybe the plugs are bad. I changed to some pricey platinum plugs. All was well for about a week or so. Now I have CEL and misfire codes again.

Like you all, the affected cylinders are random. If I run the car long enough, ALL the cylinders will eventually misfire. It just makes no sense. My wife's V70 T5 has about 158K miles on it. We love the car and we hate the maintenance cost. Seriously, we have spent more on maintaining this car since new than ANY other car I have owned. This includes a Porsche 930 Turbo. I thought no car could cost as much to maintain as that. I stand corrected.

OK forum folks....let's figure this one out.