I have a 1985 chevy c 20 standerd trans with the 454 v8. She will idle down from time to time but has high idle most of the time. Make is hard to drive and because it fluxuates i neaver know how fast i will stop when i downshift. oh 3 speed on the granny.

SOURCE: 454 on chevy won't idle

Did you check your timing? You may have the timing to advanced to compensate for the clogged filter, change your timing and then see if it will idle.

SOURCE: Chevy 454 back fire

Ignition timing is set by the computer as long as the distributor pickup point is within reason.

It could be running too lean. One of the TBI injectors may be sticking or not working (wiring or computer problem), or fuel pressure could be low.

SOURCE: 2001 dodge durango v8 5.9 trans won't shift unless i downshift

I have a 2000, there is a speed sensor located in top of the rear axel and I believe another on the tranny housing. Try the rear axel first.

SOURCE: 1990 chevy truck with 454 v8 idles too high

One thing is to leave the IAC adjustment alone, you have a vachum leake betweent the mais air flow sensor or a intake leak.

SOURCE: hard downshift on auto trans

speed sensor

Testimonial: "right on"