1993 960- Check engine light came on, and my mechanic took the car in and got the error code from volvo, but it could mean a couple of things. code 242-2 i think...anyways he was driving the car around and all of the sudden it dident like to go and started shaking with the more acceleration. So he took it in and found that the two middle cylinders were not firing. The spark plugs were checked for cracks and then switched around-no diffrence. Then the spark plug wires were swiched around-no diffrence. The fuel injectors were switched around-no diffrence. The Air mass meter was checked and was good, the timing belt was checked and was fine. Also a compression test was done and showed no diffrences in pressure, all 150 i was told. Then they took tests on if the wires were giving signal, all were fine!! Carb/choke cleaner (whatever) was taken out and sprayed around the manafould to see for leaks and if it would make a diffrence but none. The car idles very crappy and shakes and its worse on the road. The next thing they were going to do is check for continuity on the wires....but otherwise what could the answer be??? Please help, I LOVE THIS CAR!!!!!!