Well, after a few weeks of driving, one day coming home from school I noticed my CEL came on for the full 15 mile trip. By this time I had temporarily given up on trying to solve the problem, but thought that the light staying on for 15 solid miles MUST record a code. YES! It's back, the 241 code on B2. I brought it in to the mechanic to check the vacuum like you suggested and low and behold there was a leak in the flame trap piece. So, as of today I have the parts in hand (55 dollars worth) and it will be replaced on monday. I'd like to say thanks for helping out and donating your mental resources as usual - you are extremely knowledgable about these cars! Presuming this fixes all the issues, your advice will have saved me about 250 dollars - and I'm very grateful for that.

Everyone on here is very helpful, I just wish I knew enough about Volvos to contribute as much as everyone else does. So, I will post another update if and when this problem is gone.

David
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1995 850 Sedan, Naturally Aspirated, 142k mi