I have a 1994 4runner with a 3.0 and i did the diagnostic engine light test and it came up with codes 13 and 71. my engine is running very rough at idle, i was wondering if any body knew what sensor would make run rough on idle, it runs fine under load. The sensors that are on the code list are (13)KNOCK CONTROL CPU AND RPM SIGNAL.(71)EGR SYSTEM. i was told that the code 13 is a censor undernieth the intake manifold and i really dont want to take it off if i dont have to, i just want a smooth idle and would like it to be one of the others. (by the way the engine acts exactly the same when i unplug egr valve, no difference what so ever if pluged in or not) Thank you for any help!