Friend's Miata. Not sure where to post this since I dont know what kind of issue this is. It stalls when reversing uphill or holding brakes very slightly. Fuel is full so cant be tilted tank. Was thinking MAF or TPS but it never stall while driving straight. Could it be either gearbox sensor if there is one (its an automatic NA) or spark plugs/leads (these were changed last year)?

Any thoughts?

Cheers