I am the proud owner of a '92 Pearl Seville SLS, v4.9 (not quite 64,000 miles now) that I acquired with 48,000 miles on her three years ago. A cream puff that sat a little too much perhaps. Various bugs have shown up along the way and I smash them as economy permits. Aside from the delayed headlight position no longer working (it used to), and, the passenger door lock sounding as if a plastic gear is failing to mesh when remotely unlocking all doors ---- my real issue with the car is the significant engine vibration under a light load.
The car has never been run on anything but premium fuel while under my care. In attempting to resolve this problem I have spent 485.00 on plugs, wires, rotor, distributor cap and tune-up at the local Gemini Goodyear. Money NOT well spent since the car is EXACTLY as it was when I still had my $485.00. Characteristics and behaviors: Sometimes the engine seems to smooth out but usually.... the engine exhibits a rough idle (RPM fluctuating about 75 RPM at idle in drive) and shudders on a gentle acceleration (even backing out of a parking spot) most notably in the range of 1300 to 1600 RPM especially. The entire exhaust system rattles against the body.
Gemini Goodyear could not seem to find it but I pulled up a Code EO46 (also
known as PO46 on later models) in history which is "left to right bank fueling difference". This code has re-activated once, then went away after a couple of starts. Regardless when the code is displayed or not the miss is still there. Occasionally the car seems to smooth out, but the "putt-putt" in the exhaust and a slight seat of the pants feel tells me it is only smooth"er" (not smooth).
Any advice, pointers would be greatly appreciated.