when im in 3rd, 4th, or 5th above 45mph i get a realy bad vibration under load. The steering wheel shakes. The motor sound like it is bogging down, but its not bogging or atleast due to low RPMs. i noticed today it was bad at 70 in 5th under about 1/4 throttle. When i am keeping a steady speed it drives fine, and it pulls fine from what i can tell even when its shaking. I havent owned the car long so its hard to tell if it has proper acceleration. The vibration has gotten worse over the last few days. I dont have a clue where to start. The motor sounds fine when the car is parked and revved up, i cant see a major shake in the motor when its revved.

I'm kinda leaning towrds lack of air or fuel, but i dont know what to look for

It is a 98 LS with 142k miles. The CEL is on and i have code P1457 which is the EVAP canister. Not sure if its related. I am not a mechanic at all, but i am hopeing to learn on this car.

 

That code is unrelated to the problem.any mods? Sounds like a problem I had with my tps not adjusted right.

 

Sounds like an axle. evap code wont have anything to do with drivability

 

If it were an axle it would do it in every gear

 

on my drive home on saturday it stopped doing it in 5th at 70mph. it felt smooth like it should to 80. Today it felt like **** in 2nd under WOT to about 5k RPMs and in 3rd. Maybe it is an axle. How much fun is that to replace?

 

And the mods are magnaflo exhaust and an unknown intake. It has a spectra filter on it.

 

I looked in the FAQ/DIY to try to find out how hard it would be to replace an axle, but i couldnt find anything here. Did i overlook it or do i need to find another site for this repair.

 

i took the car to a shop. it drove realy bad on thursday so i stopped and dropped it off on my way home. It was so bad i didnt even want to go the 10 miles to the shop. I was close to calling a tow truck. It felt dangerous.

The shop said it was part of the axle assembly. its only 200 to fix so its not bad. He said the rear bearing on the passanger side was going too, which i did hear it screaming a few times, so they are gonna fix that also.

He also said part of the drive shaft was realy shakey, but fixing the passanger side axle should take care of that. They are saving all the parts so i can look at everything thats replaced. I also heard from a friend that if you do bearings on one side you should always do the other side? It seems like bearing are easy to do so maybe i will just do it myself.