Need some help trouble shooting rough starting, stalling on an 04 grand prix

[Yooformula]

my friends car takes sometimes 3 tries to get it to start and stay running. the car will crank quite a few times before it starts then when it does, it might stall out within a second or two and this cycle might go on a few times before it stays running. anyone have any experience with this on the 3.8l?

[Dr.Buick]

Fuel Regulator leaking fuel.pull the line and see if fuel comes out!

[85SS/85GN]

check the iac and maybe clean the trottle body

[Yooformula]

cleaned the tb, replaced the pcv, fuel filter and plugs/wires but same thing. there isnt a fpr on the fuel rail and the vatozone said that the fpr is a part on the fuel pump?! anyone replace one of these? not really sure what else to do for the stumbling, hard starts and stalling issues. forgot to mention that the check gas cap light wont go out even after they replaced the gas cap twice, fuel filler and resetting codes.

[BAD LS1]

Maf sensor failing. un-plugg it and run the car, if it magically clears up you pin pointed it as it will run in speed density at that point. A failing FPR will usually only created a long crank-to-start but will run fine otherwise. yeah the FPR is in the sending unit on these bucket style fuel systems.

This is an easy test, lets start here before digging deeper to other issues i can think of.

[brotherbenn83]

The 04 new body style GP uses a returnless fuel system, so the regulator is internal to the pump. Check the MAF first like Tom said, since it is easy and FREE. Then get yourself a fuel pressure gauge if you don't find the issue and see what's going on.

[Yooformula]

got most of it all done and its running great now but the damm check gas cap still comes on. looks like I will be replacing the evap vent solenoid. thanks for the tips guys!