Ditto for me. I recently purchased a 1994 LS 400 and its been nothing but trouble. Haven't really had a chance to drive it, currently not even driveable. The first week I purchased it the Ac compressor went out and I had to replace it ($1,500.00); also the car shutters while driving around 35-50 mph (I've seen others LS 400 owner complain of the same problem); tried to fix the problem by replacing the spark plugs and spark plug cables myself.
Once completed took the car out for a drive to test if the new plugs and cable solved the shutter problem, but the throttle is now stuck wide open and the car rpm's zoom to 4,000 rpm's and I have to shut down the engine.
If anybody knows why the throttle is stuck wide open, please help. About to give up on the car for good.
Thanks
Paul