Justy stalling

Hi, I have a '92 Subaru Justy and it's stalling on me. This only happens in the morning within 5 minutes after I get it started. The motor starts "jerking" and ticking hard under the hood, and then it stops. After that, it takes me about 10 to 15 minutes to get it going again. This only happens once, in the morning. The rest of the day I have no problems. I've been to the dealer a couple of times but they're clueless. Any Ideas? Kind regards, Mike