Harder to start when warm
 

08 5.3 LMG in my 65 GMC. Original harness, thinned. All stock except for intake and exhaust and the usual stuff removed from the original ECM. When cold it kicks/starts instantly with higher idle initially then settles down. When the motor is warm it takes about 3 seconds of crank or sometimes less and barely catches for a sec before it comes up to idle. Not a problem really just wondering why it does it.

Re: Harder to start when warm
 

Your intake and exhaust have affected things enough that your tune is no longer correct.