RB20 dies when warm. PLEASE HELP

[smellslikerubber]

i posted this in small questions thread but got no response. i figured this would get more attention. yes i have searched and searched for a solution to my problem. been chasing this issue for about 2 months now.

I have a 91 240sx with an rb20 swap. Haven't had it long so im in the process of working out all the small odds an ends from previous owner. Car runs great, a bit rich but I think its due to the timing be a bit off which I plan to fix in the next week or so..but anyways more often than not the car will just die once the motor gets hot. Or after about 10-15min of driving. (Previous owner informed me of problem and said he had tried almost everything. I call BS) i thought it randomly occurred but noticed that it does it mostly when i start and drive it for the first time that day. sometimes it Wont do it for a day or two but then it comes right back. Idle or 60mph it just dies. No sputter or kick. dies as if i turned the key off. when this happens it kicks on the check engine light. i noticed that once the motor cools the light goes off and then it starts right up and drives away. no i havent hooked up to a scanner yet, having trouble finding one for the older OBD1 port. it used to take 10-30min before it would restart but i found that letting the fans run it takes about 8min (yes i timed it) Searched here for the answer when I first got the car and was told to try coolant temp Sensor which I did(bought from Nissan) i thought that had done the trick!..But it still happens. im trying to give all the information i have and know. Any ideas? Im willing to try anything. Trying to get car ready for track season

also previous owner said it has a Z32 MAF. Could it have went bad? If so where is a good place to get one? I know they can be pricey

could i be loosing spark? making it something ignition related?

also have Z32 ecu. i have made sure it was not getting hot in its current location.

Thanks for the help