I have a 1998 Cadillac Seville SLS, the problem is when I'm in traffic around 15 or 20 mph and a tap on the accelerator it gives a knocking sound, like it was the motor mounts, but I had transmission mounts and motor mounts replaced and it still does the same thing, I took it to Cadillac and they tell me my Excelerator paddle was sticking, so they fixed it for a hefty sum, I went for a test drive and it's still there, the service guy at Cadillac told me there was no readings on the computer stating something was wrong so now they're going to contact General Motors and find out what the problem could be.

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1998 Cadillac Saville SLS Eight cylinder