92 Dakota 5.2 liter starts and idles fine. Runs good under accelleration and decelleration but sputters and bucks at cruise speeds above 55mph. I've done plugs, wires, cap, rotor, oxygen sensor, a

SOURCE: 1992 dodge dakota starting problem

The first thing you need is to have the unit scanned. Check things like the baro sensor,map sensor,coolant temp. and the TP sensor.Also check your fuel pressure,volume and injector spray pattern. I think you will have found your problem,but if not hit me back with engine size and any codes,Good Luck.

SOURCE: engine runs rough and bucks at 1500 rpm

check fuel injectors for debris

SOURCE: sputtering when accellerating

In adequete fuel pressure change the fuel filter, first depressurize the fuel line. run dry gas in the vehicle once a month. Check for OBD codes it may need a MAF sensor.

SOURCE: bucks or jerking feeling cruising at highway sppeds

It sounds to me like the drive train is getting loose. By loose i mean that the universal joints, and linkage to the rear differential is worn.
The engine speed is trying to adjust to keep the speed sensor from the transmition to the cruise, and the speedometer constant. when the engine begins to slow down, or speed up the loose drive tran will be amplified by the loose linkage. It is easier to notice this problem with a standard transmition.
If it has a stick shift and you are in a low gear try speeding up and then letting off the accelerator and it will ****. If it has an automatic it will not be as evedent but you can try putting it in the lowest gear and do the same. It could have a clank sound when you hit the gas, or when you let off the gas, but not always the case. If the universal joints are going bad it may have a vibration when you get up to 40 MPH or so. This will shake things apart if you wait too long.
Also if the universal joints are wearing out it could have slop in it when you have it parked and give it a strong wiggle from the drive shaft just in front of, or just behind the universal joint.

SOURCE: 97 Dakota, 3.9L, 2wd. Engine hitches when warmed up, idles fine.

has anyone put the lab scope on ignition yet