alright i have a 1966 Mustang with a 3-speed auto w/ overdrive. and i dont know if it was like this when it was made, but my transmission will only shift if i hold down the pedal and take it to the redline for 5 seconds. and the one time that it shifted lately was at about 65~70 MPH .was my car made like that or do i need some work done, because my fuel economy is absolutely killing me! (getting about 8-10 with 4-barrel and bone stock 289)

 

oh, and i should probably include that i just changed from a holley 2 barrel to an edelbrock 4 barrel, but before that it was the same deal with the tranny

 

No tps on 66's. You either have bad vacuum modulator or "kick-down" linkage not adjust right or missing. Not sure which this trans used, but that is where your problem lies.

 

i think that it could be the kickdown linkage...but im going to have someone check it out today