1995 Volvo 940 Base review from North America

-Temperature gauge no longer works.

-Having hard to diagnose engine trouble. See comments below.

-Front bumper cover mounting clip has snapped on the passenger-side near the wheel well, so that side sags.

-Front turn signal covers are yellowed, brittle, and road stones have put holes in them. Typical for these Volvos.

Front the list above, you can see most of the problems I've had with my '95 Volvo 940 have been very small, minimal problems, especially given the mileage on the car. I can accept these problems.

My main complaint is with some engine trouble the car is having. Since I bought the car 1 year ago, I've since put about 15k miles on the car. From the time I bought it, it occasionally made a random pinging/rattling kind of noise from the engine. Over the past year though, the problem has gotten worse and worse. Now, it occurs everyday I drive the car. The odd part is that it comes and goes while I'm driving. It'll ping and rattle excessively for a few minutes of driving, then the problem mysteriously stops completely and the engine sounds and feels much beter... smoother and quieter. Then at random will, it starts making the racket again awhile later while driving. I've noticed the smell of gasoline when I come to a stop, but I have checked and no smoke is coming from the tailpipe. I go to different filling stations, so I know it's not an issue of cheap gas I'm running. I thought maybe the timing was off, so I brought it to my trusty Volvo mechanic, who checked the timing, said it is fine, and said the timing is actually self-adjusting on these cars, so it can't be manually adjusted anyway. I love the car for its safety, comfort, fuel economy, and general reliability, but this problem has got me at at the end of my rope. I thought maybe the computer that adjusts the timing has gone bad and not adjusting the timing properly. This would explain the engine pining/rattling, the smell of gasoline, as well as the lack of power when all this is going on. I don't want to invest several hundred dollars for a new computer though because it's not a returnable part, in case that's not the problem at all. Does anyone have any tips or advice? What's gone wrong here?