1999 Tacoma 4x4 Trouble starting once engine is warm

I can start when the engine is cold, but once it's warmed up, i have trouble getting it started. I usually have to give it gas or it will idle at 500 RPM for about two seconds and then die. Once I do give it gas on the start-up, it fires up and idles like normal. Today I changed the spark plugs, plug wires, timing belt, fuel filter. Thinking that this might fix my problem but it hasn't. The timing was off 10 degress. Engine does run alot smoother now, but still wont start if engine is warmed up.