Only has lean codes Bank 1 and 2 new oxygen sensors but still idles ro

[Mark Lee]

I have a 2000 GMC Sierra with a 5.3 liter. The truck starts perfect right away when it's cold but if it's warm it cranks for a while before it will start and then it wants to die but doesn't most of the time. I can feel it cutting out on the highway but it doesn't show any misfire codes. My O2 sensors up front are new but read High as if I have a vacuum leak. Going around the entire engine with WD and Brake clean I could not find any leaks. I've changed the fuel filter and now I'm at a loss any ideas?

[silveradosid]

check fuel pressure regulator, pull the vacuum line off and see if there is fuel in it

[rjgti]

intake gasket maybe

[txab]

Take fuel pressure reading. Key on, engine off reading and post back

[Mark Lee]

Thank you guys for the replies and suggestions. I should have mentioned fuel pressure is a steady 55 PSI. As per your suggestion, I checked the vacuum line to the pressure regulator and there was no fuel in it. I was leaning towards intake gaskets myself since that seems to be a common issue with the 5.3L. I bought the gaskets today and hopefully will have time to throw them on tomorrow. I'll let you know if that resolves the issue.

[Mark Lee]

Silveradosid, it was the Regulator. I checked it before and didn't notice any gas in the vacuum line so I got the gaskets for replace the intake manifold gaskets and when I went to pull the vacuum line gas came out. I didn't do the gaskets I just changed out the regulator seems to run fine for now and hasn't popped any codes yet. Thank all of you for your replies

[Mark Lee]

Here's another question for you guys and let me know if I need to start a new thread for it. In the last few days my 2000 1500 GMC Ciara is stuck on defrost doesn't want to change from floor to vent or anything else. Tried resetting it battery disconnect all that. Do you know exactly which one of the actuators controls that or do you think it's in the control panel?