difficult start, low idle
 

Just started the WRX (MY95) up to get ready for the MOT next Friday. Started first time, clutch down, no throttle and ran up to temp fine. Switched off.

15 mins later wouldn't start off the key as above, needed pump of throttle. Lift off and idle drops down to 250rpm and dies. Needs throttle to keep running though if i am careful i can make tick over at 250rpm

After of while (5mins?) of 250rpm the revs rose to normal idle and it ticked over just fine.

tried to start later and same problem but returned to normal idle after a while.

disconneted MAF when running ok and the car died (i remember that proves something so i am off to do a websearch on what)

Anyone have any ideas why it's doing this so i can correct?