1998 boxster 2.5l Stalling and start problems!

[Ok_letsgo]

Hello my forum colleagues,

I have a problem with my boxster for 2 years which I need help troubleshooting and eventually repairing.

Cold starts ok and idles fine and drives well.

As soon as it gets warm say after 20min driving, the car will start to idle hunt then it will sometimes stall and turn off as if it would not receive enough fuel to keep the car running always on ramps and steep hills.

Usually when I park the car and return after shopping or gym I turn on the egnition to turn over engine then it would seems as it would flood itself and won't start,
Till I pump the fuel pedal then eventually it does turn on.

Just recently 1 day before this post I tried to start the car and for the first time it backfired! that loud that the people in the car parked in front of me dropped to the floor as they were putting shopping in the boot of their car, thinking someone was letting off a round from their semi automatic firearm. Me too!

Over the years I have read a few forums and repaired or replaced the following so you can exempt these,

New MAF sensor

Cleaned Idol Control Valve

Cleaned Throttle Body

New spark plugs

Air filters etc

Oil services (replaced)filters

Same premium unleaded

Note:

My mechanic says it does not throw any codes when he hooks up his handy looking unit monitor!

If anyone could please give me a resalution to this problem before I go spend $3500 on changing the fuel pump and relay which my mechanic might think the problem is.

Would be great

Thank you guys any help would be appreciated.