i'm a newbie here, so maybe this has been posted already.

okay, here's the rundown:

'93 DX 1.8L SOHC 5-spd. 142,000 mi. no mods.

for the past few months, i have had a very strange stalling problem that occurs when i'm idling at a light. this has been happening on average ~once per week, always when the engine has been warmed completely. the RPMs drop slowly from the usual 750 down to a stall, and the car won't want to restart for about 5 min. if i try, the engine restarts for about a second, and stalls again, and will continue to do so for several minutes. if i wait about five minutes, the car will start right back up as though nothing every happened, and i'm good to go for another week or so!!!

no other symptoms-- engine idles perfectly otherwise, no HLA noise, no rough running when warm or cold.

my mechanic has looked at it twice, and claims everything checks out fine, and of course can't reproduce the problem 'cuz it's so damn infrequent!

ALL maintenance done according to schedule using genuine mazda parts. the air/fuel filters, dist. cap/rotor, plugs, plug wires, PCV valve, etc. were replaced within the past 10k mi.

i'm thinking maybe TPS? idle stabilizer? EGR valve? air intake sensor?

anything else i can recommend for my mechanic to check?

thanks!