Check the warm air intake system: air cleaner diverter valve, temp sensor, exhaust shroud & tube. With the weather you've been having lately, (30 to 50 degrees) this system is extremely important to prevent ice-up in the throttle body during warm up.
Also:
Check injector spray pattern
Check wiring at injector connections
Check fuel pressure
Check fuel filter for restriction
Check TPS wave pattern, (make sure it's smooth)
Check MAP sensor