Have to get a gauge and check (I don't have a gauge), but.....does Po171,Po174 and hard start after sitting for 10-15 minutes sound like fuel pressure regulator?
1999 4.2 V6
Thanks!

 

I'd change the fuel filter first. Also sounds like some leaky injectors and a major vacuum leak.

 

Thanks, did change fuel filter but same symptom.
Can't find a vacuum leak (replaced elbow a while back). Runs ok, a bid hard on fuel. Biggest issue (besides CEL on) is the hard starting. Shut off, it'll restart fine. However, it'll crank a long time (10-12 seconds or more) if it sits for more than, maybe 10 minutes. Cold start is ok, not like new, but reasonably quick.
Leaky injectors? Guess that could be it, makes sense.
Thanks for the info.