Catalytic converter?

I have a 98 ford contour svt. I have been having some problems with it idleing. When I start the car, only sometimes, it won’t stay running and dies. my check engine light had come on and the auto mechanic said it was for my catalytic converter code. he said if that was really the problem it would do it all the time. he cleared the code and off I went. A few weeks went by with no problems. Then one Sunday it did it again and the light came back on. since then its done about every two to three days. it seems to be happening more often. The last time it did it, i brought it back to him. By the time i got it there it wasn’t doing it, so he could not diagnos it. no one is around when it seems to happen. I just keep turning the car off and then on until it decides to run. Any suggestions, I am running out of options and dont have the time to play this game with my car. I have places to go! Please Please Please HELP ME!!!

Find out what the alphanumeric code is. Will it keep running if you step on the accel pedal just a little?

if the light was on, it did store a code. instead of just erasing the codes, find out what the code (s) actually are, and post them back here.

the codes read like this: P 0123 or P1234. post the actual code, not someones interpretation of it here.

i suspect you need to find a new mechanic as well. (just my take on it from afar)