ATTN MECHANICS: strange car problem. HELP.?

I have a '93 Lexus ES300 that does something that has so far baffled everyone, my mechanic. I will be driving down the road and, it'll begin to shake the steering wheel goes back and forth, nearly like I am driving over a bumpy road, bluish white smoke begins pouring out from under the hood and the body of the car, and it starts acting as although it is either stalling not enough gas or being flooded with gas. My mechanic said that when he checked the emissions canister, it was full of gas and nobody looks to know what the problem is. Any ideas could be appreciated because I desperately need my car to run as I work and go to school 70+ miles from where I live. HELP.
I should add, my mechanic emptied the emissions canister because it was full of gas and gas was really running out from underneath the car when I brought it in. The car has done this two times now and nobody can figure out what could because all of the signs.

if the charcoal canister filled with gas there must be a problem with your vapor recuperation system.The fuel return line being clogged is possible.A bad check valve or pinched/clogged hose someplace comes to mind.I don't know any specifics about the vapor recuperation for your Lexus,but I could say that could be where to start looking for a problem.

i don't know, but call in to a radio show called the car guys on national public radio on saturdays. they answer questions every week and generally seem to know the solution to the problem.
and its free..

hi,i am to ask you some question. did you mechanic check for codes,did he check the fuel pressure. if he did all this and allright then attempt to drive you car with out gas cap, if this crack the problem you have a problem with vaccum routing or you gas cap. if I can't fix you car I'll go to work for mav donald o.k.keep me on touch

The problem sounds like a tank pressure problem. You did not identify, but I assume that the car is parked indoors or in the shade in the AM. The fuel in the tank cools overnight and sucks air in via the gas cap to preserve equal pressure. As the car can be used in the sun, the gas expands and builds unbelievable pressure. This pressure is then relieved through the pressure release valve over the tank. If this pressure valve is faulty, the pressure in the tank supercharges the fuel in the lines and dumps up to six times the fuel every time the injectors open. This increased fuel pressure floods the engine and effectively stalls each cylinder for 1/4 revolution, causing the pcv system to blow out a lot of smoke. nevertheless so much for the explanation. Now for the cure. Have the roll over valve changed. To be sure that this is the problem, unscrew the gas cap in the AM and drive with it loose. If the problem doesn't reoccur, it is the valve. If it does happen, have the ignition module checked out as this problem could also be caused by the module advancing the timing too far..