I've been getting rough idling and almost stalling at cold startups for about a minute then it'll idle fine but i thought I'd check my fuel pressure and it went to the high 40s and immediately dropped. It slowed down once it was under 20 psi. Is that normal? Or is it supposed to hold? While idling it stays at 40 PSI. I have new fuel pump, fuel filter, injectors, fuel pressure regulator. 87 5.7 TPI. Thanks.

 

Bump

 

As stated in the Facebook thread, the bleed down of the pump is normal.

Have you reset your idle, and IAC? Run through that procedure. Clean the IAC passage. Check to make sure the IAC isn't junked up thus not working right/sticky. If it looks rough, replace IAC.

Also, since you did all that work, check for vacuum leaks on the plenum/TB gaskets.