Mr.CrownVic

I just bought this 86 Crown Vic w/ 5.0 , she runs great throughout 1st and 2nd, when it shifts into 3rd it loses power, flutters and stumbles until I mash the gas to the floor, it downshifts with lots of power and eases up a bit when it shifts back up to 3rd and has hit about 40 MPH. I had this same problem on my 75 Ford van three on the tree but that was Carburated. I put a new carb on it and fixed the problem. I don't know much about Fuel Injection and all the sensors that come with it. I cleaned the throttle body and installed new plugs, wires, cap, and rotor. She also stumbles a bit on the highway and has a vibration that doesn't seem to be coming from the tires or driveshaft. Anyone have a clue at what is going on? Other than that, it runs sweet.

 

Bingo

I have the same car as you, and all I have to say is the gears are REALLY high. There's a slider of sorts on the transmission that will control your shift points. My father adjusted it, so I don't know which way to slide it to make it shift harder, but adjusting that would help. It will wait to shift, rather than upshifting at a low RPM while going up a hill.

It's meant to be a cruiser.