'95 Marquis Has Trouble Accelerating

[WRBsGTP]

I need help trying to figure out what's wrong w/my grandfather's 1995 Grand Marquis. It vibrates hard when accelerating on the highway--especially around 2nd gear. It's really irritating, b/c its acceleration pretty much stops until the vibration goes away. I'm pretty sure it's not the transmission, b/c it shifts smoothly between gears.

The car only has 20,000 miles on it and everything's original. (it just got the pvc valve, fuel and air filters changed for the first time). The wires are all original. Do you think a tune up w/new wires and spark plugs would fix this problem, or is there something else I should try first? Any help you can offer is greatly appreciated.

[cobradude360]

have u looked for any vacum leaks or cleaned the throttle body mayb take a few plugs out and look at the condition there in

[fredjacksonsan]

Definitely do a tune up, and if that doesn't fix it, checking the Ujoints would be my next move.

[WRBsGTP]

cool. i didn't think to check for vacum leaks. just curious fred, what are ujoints?

[fredjacksonsan]

The drive shaft comes from the back of the transmission, and goes to the rear end. There are two points, one near the transmission and one at the rear end, where there is kind of an "X". Each of these is a universal joint; they allow the rear end suspension to work (go up and down) without slamming into the transmission. The universal joints are X shaped units that fit into the driveshaft. When they go bad you'll get vibrations while driving.

Hope that was clear.

[ALAN5521]

I don't know if you ever got the problem fixed or not, but, for what it's worth we had that same problem with our 95 Grand Marquis. The problem was the catalytic converters. They were clogged up. We replaced them with used from a wrecker and got another 2 years out of it before it happened again.