Not sure if the V8 fuel rail has the Schrader valve test port (V10 does), but it is an easy test if it does. When this happens is it after the truck sits or every time? If every time then the pressure may be bleeding off due to failure of either the regulator, pump or a leak in the system. The filter is not likely to be your problem.

 

only reason i say filter is because in my haynes book its listed as filter/regulator. like it is the same part.

 

It is the same part. The filter is inside the regulator and is changed as an assembly.

 

O2 sensors are not read on a cold start. They must heat to operating temp.

 

ok aim, forgot about the open loop thing. i have a question about a recent post. do ya'll remember the one about the evap purge solenoid on the passenger fender on the 98+ rams and behind the drivers side of the intake manifold on the 94-97s? i think i figured out the problem.

read this-- https://dodgeforum.com/forum/2nd-gen...-starting.html