my car after it warms up will stall out if i take it out of gear and let the rpms drop from above 2000 and sometimes wont catch itself when i turn my car back on after it stalls.

my mods are:

blitz SUS short ram intake
Turbo XS UTEC
Borla headers
HKS uppipe
HKS downpipe
HKS HiPower catback
stock turbo w/ 18psi
650cc injectors
255lph walbro fuel pump

i have 243whp and 249 lb/ft torque

i have also had misfires under full throttle in fourth and fith gears in all four cylinders. i really really dont want my car to blow up so can somebody pleeeease help i replaced the turboxs blow off valve back to stock

please email me at Primeevil51@hotmail.com if you think you know what the problem is