98 S90 below average performance?
 

Help all, I’m new to the forum and to the Volvo world somewhat. I have recently acquired my first Volvo, a 1998 Volvo S90 with only 128k miles on it. A couple of things I’ve noticed after owning it for about a month now is I occasionally will get a random stumble or miss at idle that last maybe half a second and goes away. Sometimes it’ll do it twice consecutively and go away. No CEL however, and I also noticed it seems a bit sluggish in acceleration especially from a stop but even in general, especially at higher rpm. I don’t know what these are capable of performance wise but it just seems less than it should...

I’m getting 17-18 combined (mostly city) and I checked my fuel pressure and it was about 45 psi or so which I read is where it should be. Any help would be appreciated.

Take it out of economy mode, put new (correct) spark plugs in it - and report back.

it’s been out of economy mode since I bought it lol hated the shift points, not that sport is really that much better (or at least for what I’m used to an auto box to behave).

it had original volvo plugs in it which had no tip, replaced them with NGK platinum plugs with the correct gap and it made minimal change. I’m wondering maybe fuel filter, and/or clogging cat possibly? (From low quality and/or not using premium fuel?)

The 91- 97 960 with the b6304 had ~200 hp, the 1998 had 180 hp. It will be sluggish compared to other 960s with the inline 6

im aware of the power difference after 95 for emissions and the change in cams etc. but it still seems slower than others I’ve seen in videos and than what they’re rated for. I did a 0-60 one day and it took like 10+ seconds timed with a stopwatch

yeah I figured it had to be in the 8-9 second range. My exact time was 12 seconds I believe but I may try it again and see how consistent it is. But it’s not gonna get much better I know that. Even if it was less than ideal environment etc. it shouldn’t have added an extra 2-3 seconds…

and of course my random stumble or miss that last a split second that I get occasionally at idle.