95 f150 5.8
What things can be checked or replaced to keep the truck from running lean?

I'm getting low throttle studders. Runs fine when throttle opened up and idle. Code reads lean on the o2. The CEL very seldom comes on the goes out. Thats the only code I have.
I have put new plugs, wires, fuel pressure regulator, fuel filter, rotor and cap, and cleaned the throttle body and also a new TPS. EGR seems to be working, atleast I see it moving up and down with the vacumn hose check. What else can I do?

 

Running lean, too much air or not enough fuel. What about the exhaust, could it be sucking in air? Back in the early days of smog checks, test equipment would lock us out if the exhaust system was perforated and sucked in air, screen would say 02 lock out. Now remember I am talking back in 1982 in California. Inspect the system from the 02 sensors upstream to the engine.

 

My truck was doing the same because of fuel pumps. Check fuel pressure and post the results in here.

 

...yeah I'll have to check for pressure guage, surely they can't cost that much. You check that on the fuel rail correct? I think numbers should be around 35lbs or so?