This appears to be a very common problem with 90's camry's and I wanted to post how I fixed the problem. I tried a couple of mechanics and none were able to diagnose the problem. Fortunately a guy on the UK toyota owners group figured this out. His name is Ive and he is from British Columbia (just wanted to give him credit). His mechanic found the problem by running diagnostics on the car as it was running.
The symtoms of this problem are that when the car is started and is cold the car runs fine. Once the car warms up a bit it will stall whenever you stop. Also some people complain that they smell a strong odor of gasoline.
The problem is the coolant temperature sensor. These are consistently fail in 90's camry's. When I went to the toyota dealership and asked for a coolant temperature sensor the parts guy gave me this exploded parts diagram of the engine that showed about 10 sensors that were abbreviated. That confused the hell out of me. So I went to a local parts store called VIP auto. They were very helpful. I told them I had a 94 camry wagon 4 cylinder and they ordered a KEM brand coolant temperature sensor part# 140-715. $35 part. I figured it was worth a try.
This is how you find the sensor. Under the hood, top of the engine, next to the valve cover, a little bit towards the driver side is 3 different sensors. Quick connect wire couplings come off the top of each sensor. I figured out which sensor it was by looking at the connector on the replacement part. On my car it was the sensor closest to the center of the car. Squeeze a clip on the sensor and the coupling comes apart. The sensor threads into the coolant output line coming out of the block of the engine. I used a 3/4" box wrench to loosen the sensor. Since the sensor is above the rest of the coolant system, barely any coolant comes out of the pipe AS LONG AS THE CAR IS COLD. Out with the old, in with the new and my problems are completly solved. This is a brass sensor so don't overtorque it. Just get it snug.
I was so appreciative of the guy who posted the fix, I felt it was my duty to post the fix for more people on google groups. I hope this helps some people like it did for me. Good LUCK!