my 96 I30 has a new (used) engine with 50k miles....but it idles pretty roughly....when the door is open you can see it moving with the engine as does the passenger seat when unoccupied. It moves back and forth quite a lot annoyingly! ALso, when driving the steering wheel and stick (5 speed) vibrate and shiver....its not that bad under 60 but very bad a 70! It lessens around 80.....but is always present to some degree....it also seems to come in cycles starting smooth and get progressively worse in about 5 sec intervals. I know this car had a front end collision from the first owner, as the right fender is slightly misaligned with the hood as are the fogs and turning lights. How many possible thing could be wrong? In regards to the vibrations, I recently changes the oil filter spark plugs, pcv valve but need an air filter. Could the motor mounts be bad? Shouldnt my mech have noticed if they were when he installed the engine? Could I have just worn bushings? Or maybe some major componants of my suspension is bent? I also though I might hav a bent rim, but the car did the same things on the OEM wheels....the tires are worn badly on the wheels, which may account for some of the problems, but def not all! This vibration is driving me nuts! It feels like my car is falling apart! I plan on keeping this car for many years, so finding and fixing this problem is def worth it! If anyone could help me by listing as many possible things as athey can think of that could be causing this problem Il be able to go own the list and check them off....I figure I need to start with all new tires, making sure no wheels are bentm an alignnment and balancing, to start diagnosing the vibration problem....I dont know if the vibration when idling at a stand still is related or linked to the vibrations and shakling when driving, but I assume not.....help me out!!! thanks!

You have two seperate issues.

One being the vibrations at high speeds which generally is wheel and tire related. It could be suspension related as well, but the wheels and tires are the place to start. You mention the tires are worn badly, thats your first place to look.

The rough idle could be a misfire of a motor thats got a dead cylinder. Did you mechanic do a compression test to see if your new or used motor is really in good shape? Do you have a CEL light on, and more important, is the CEL light bulb working? (comes on initially when you turn the key to the on position)

Perhaps you should find another mechanic to give you his opinion on the problems your having.

actually I have had a cel for over a year....its an egr problem and O2 sensor problem....I have 1 front o2 sensor but I havent actuqally installwed it yet...I have had the egr system flushed but the code is back so I am going to replace the egr valve when I get a chance....after this, well see if the idle smooths out...yes I need to replace all the tires, make sure no wheels are bent and have an alignment and balancing done...I guess I should have waited to do all this before posting, assuming the problem persists after everything is replaced.....no I never actually did a compression test although the guy who sold it to me said one was done and listed the compression for all of the cylinders which was within spec....I guess if I still have this problem after I replace the things above, Ill do that.....about how much is the test anyway? thanks for the info!

definiatly the igniton coils doesnt matter what year 4th gen maxima, they all have the same problem over time, they melt.