Well i got a 1995 grand marquis. Well for some reason when im giving it gas around 50 miles per hour it like jerks a bunch of time. Its not the fuel filter, spark plugs or spark plug wires, i just replaced those thinking it might of been the problem. But it only does it at these speeds. Oh yeah could somebody show or tell me where the police interceptor chip is located on the motor. I bought a 1997 crown victoria and it gots the police interceptor chip in it, and i wanna put it in my marquis. Some pics would be nice.

 

Is your check engin light on at all?? Does it make a difference if you have the overdrive on or off?? Being that it does this at a specific speed it sort of sounds like you may have a dead spot in your TPS...

As far as swapping the chip, there is no chip.. The PCM is programmed... You would have to swap the pcm, and I'm not sure if they would swap.. According to the Hollander interchange, and the interchange on the Kragen web site, the 95 PCM is specific to 95.. By 96 the PCM had to monitor alot of emission whatnot to meet federal standards.. Not all of the same stuff was monitored in '95 and back.. But, you could always try swapping them and see what happens.. The PCM is inside under the dash to the left of the steering column.. It'll be a silver box that bolts to the fire wall and actually goes though it to an electrical connector under the hood.. You may be better off finding a 95 PI PCM or getting some sort of aftermarket programmer....

 

I agree with the TPS idea except I think it's a dirty one (internally in the contacts). It sounds like the computer is having a hard time at that point determining the gear to shift into. Once the signal stabalizes, it'll shift. There could also be an issue with the speed sensor. If you have any issues with the cruise control not working right, that may be the issue as well.