Violent jerking and vibes on highway

My 96 Ax-15 has been occasionally getting a violent jerking on the highway when I hit the gas to accelerate in 5th. This has been happening for a while but very rarely, maybe 4 times in 15,000 miles. The past two days it has done it a few times and it is violent jerking that can be felt through the whole drivetrain. It does it for a second and then goes away and drives fine

Also I have been having some on and off vibes that feel like they could be from the trans mount area.

Any suggestions?

I'm newbie, but lots of experience in other types of vehicles, so take this with a grain of salt;

It sounds like "U"-Joints to me. I'd look into driveshafts and drive angles after that. Is your XJ raised?

Also check your motor mounts, if they are squished and worn out, the motor mounts will squish and change the angle the motor/trans sits and change the drive angle. As well, worn out motor mounts will allow the engine to jerk and rotate excessively, which can feed into your problems.

I got a Passenger Side Motor Mount from NAPA and the Driver Side coming thru mail order, I'll be putting them in soon. I was getting annoying jerking and clunking that was unmistakeably motor motion, I wouldn't classify it as violent, so I'm guessing your driveshafts/U-joints are the cause, Motor Mounts may be contributing or the root cause.

I will check all the drivetrain parts and mount again. The tranny mount is soft and I will replace that this weekend. I've been meaning to for a while

The main issue is the jerking on the highway. I replaced the plugs, wire, cap and rotor 10k ago so I doubt I could be missing. Would a TPS fould out like this and cause quick violent jerking

I doubt violent jerking at a certain speed is from the motor. If it was the motor, the jerking would happen at a certain rpm and you'd get it several times as you went thru the gears.

I'd suspect something in the drivetrain, like "U"-Joints. The output of the trans will not cycle in RPM, it is directly proportional with speed. Thus the output of the trans/driveshafts/u-joints/axles could suffer violent jerking at higher speeds but not lower, totally independent of what gear your in.

U-Joints do wear out, they bind themselves or they get slop in them and allow unintended changes in the angles between shafts, that will cause binding, this would cause violent jerking in the drivetrain.