My 1992, Lexus just started to jerk slightl and the engine light came on so I ran the code and it came up 13 RPM circuit fault. I took the car to a toyota dealer and the did a 3 hour diag and said it was to deep of a problem and that they could not pinpoint the issue. The ing and related were checked but I dont think they checked the cam sensor. I hope you can help me I actually thought the dealer would find it and fix it but I'm back to square one. Please help me with this problem.