Wow! You guys are scaring me. The car ran fine and no CE light was on since we bought it in January. The winter was very cold and snowy and the car ran like a champ. I really admired the way she handled snow and bad weather being RWD and all (I think all that RWD bad rep is due to over-powered, under-suspended old detroit RWD monstrosities anyway). The car was never really taken on a highway much. Just a daily hauler for my wife and kids. Last week my older son had camp outside the city and we used the 240 to drive him there. This trip is a mix of city and highway. Highway being uphil in one direction for a bit. I noticed some pinging (for the first time since we've owned her) on the uphill highway and a bit of a power drop-off. No CE light at that time. In fact we went the whole week driving back and forth to that camp with no CE light. Then, during the weekend the light came on accompanied by occasional hesitation during idle and more pinging. Are my knock sensors ok? I will try to test the air mass meter (not sure if I'll succeed) and the fuel pressure regulater.

Thanks guys for all the help. If anything else comes to mind, please let me know.

Cheers!
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Vladimir. '98 S70 base, 5-speed manual (his), '91 240 sedan automatic (hers).