Here's the description: after letting off the throttle, the engine violently shakes, enough that I can visibly see the radiator hose bounce around 1/3 an inch and the entire engine shakes then stops. Inside the car when accelerating the steering wheels shudders violently, then levels out. Then when letting off throttle also shudders. Above 2k revs its FINE.
Had new ignition coilpack, plugs, o2 sensors, etc done in June and ran great until now. Cleaned fuel injectors but didn't help. Would clogged fuel filter cause this?

JUST today when starting the car it felt like it was going to die then surged and idled usually.

 

The reason I'm thinking its fuel related is because at higher revs more fuel is being forced thru, and at lower revs the lack of fuel causes it to shudder. But what I'm curious about is how that would cause the engine to shake so violently? If the problem was consistent and shook at all times I would have blamed a faulty ignition

 

I thought bad mounts at first but being that it dropped in RPM's and surged back up is kinda odd.

Try cleaning out your IAC, this can cause the poor idle quality and why it goes away after 2k rpms.

It wouldnt be a bad idea to pull your EGR valve and make sure its not caked up either, its a lot harder to clean that as the crap gets baked on in it, I chipped the crap out of mine with a screw driver.

Anyways, check and clean that IAC first and be sure to get a new gasket first and clean both surfaces so it seals again correctly.

 

You should also seafoam the car too.

If you havnt done it before I would go through the intake twice and the last third through the tank.

 

I think saefoam is thrown around a little too easily without thoughts to the harmful effects it can have. One I know of is breaking loose old stuff and it clogging other stuff up. If an engine is old or not taken care of then saefoam can really give you a headache.

 

Yeah I seafoamed the intake last month and it ran noticeably worse. The previous owner of my car did not take care of it at all so I'm trying to show all the mechanical love possible to have it good again. I'll check the egr valve when possible, I have had previous problems with it before but it didn't make any negative effect, just finger loose. How can I access the IAC?

 

Also if it was bad mounts how much am I looking at to fix it?

 

I do believe it suggests not using it on cars over 100k miles if you do not know the condition.

It can cause problems for sure if the engine has been neglected.
If the car has burnt valves the shock of the Seafoam could finish off causing total loss of compression. Thats what happened when I seafoamed our 210,000 mile 96' Honda Civic (That POS waste of money, thats what I get for buying at auction.)

 

What can I do to maintain the engine besides maintaining fluids, ignition, etc? I seafoamed my intake with my car at 192k miles.

 

I'm going to change the fuel filter out soon as possible, and put in some new cats. If the problem persists I hope its nothing serious..