wacky ignition

after its been sitting awhile, it cranks and doesnt fire up, turn off ignition, fires right up. Starts perfectly fine when warm. Changed from regular oil to semi-synth a week ago. Its been doing it every start-up since a few days after the oil change.

'99, 130K

i dont think oil has any thing has to do with it.

have u check if the fuel pressure's down after a while, when it cold , see if there is any pressure in the fuel rail.

Would be nice if u told us the year. We like info.