Ok I have been lingering here for awhile to get a solution to my problem, and have searched everywhere for the answer to these problems and here's what I've done for my 96 4cyl Camry (145K miles):

#1 CEL, P0401. For about a year and a half, I just drove with the damn thing on, because I couldn't find the crow's feet anywhereto removeexceptSears, and they wanted$45 for the set. After passing emissions 2x by clearing code,driving for 20 miles, I decided I really needed to tackle this thing

-- Removed EGR Valve, cleaned in carb cleaner (it really wasn't that bad, affirmed that the diaphram would pop back into place by pushing up and down. CEL returned.

-- Replaced Modulator cleared code, CEL returned after 100 miles of driving.

-- Replaced VSV (that's a real pain in the butt), cleared code, and CEL reappeared after 100miles or so.

QUESTION: Could the code be coming on because the EGR needs a new gasket? Could the EGR be bad even though it seemed to function correctly?

Also: The car has a noticeable vibration at idle. You feel it most in the steering column, but really the whole car has a noticeable vibration. I have change ALL 4 mounts, and still the damn thing shakes.

QUESTION: Could the shaking be related to a bad EGR valve? Could the EGR valve have killed the catalytic conv, causing P0401 and shaking? Are these two symptoms unrelated?

Finally:

When I am going 25-50 mph and I let off the gas, there is a noticeable thunk (seems to be coming from front right of engine and occurs at shift.) If you give slight gas and then let off you'll get a thunk, thunk on the upshift and on the downshift. Can this be caused by a bad half-axle or does it sound like the tranny, OR could that rear motor mount (that I just installed), have gone bad? (purchased at Autozone.)
Two otherthings: (when turning I hear a clicking SIMILAR to bad CV joint, but not quite the same.) Also, pulled off tire yesterday just to take a look at axle--both boots inner and outer looked fine, but there is about an inch of play when you try to turn the rotor when the car is in park...Is this normal?

THANKS!

 

CEL P0401: Ever thought it could just be the sensor?
Reference: http://www.obd-codes.com/trouble_cod...n-flow-egr.php

 

I was under the impression that a 96 camry doens't have a DPFE sensor. As I said before, I changed the vacuum modulator, and the VSV.

 

You needed to look farther than the first line of the reference link. If you scroll down a little you'll see forum discussions on your problem. There are a few on the Camry and Corolla that may help you. I didn't think you wanted me to do all the work.