so my 02 expo 4.6L hesitates at idle and during acceleration. not all the time, it's pretty random. it does this hesitation at high speed on the freeway and at take off from a stop.....anytime. i've done a lot of research and a process of elimination and the problem still exists.

here is what i have done to try and solve the problem
replaced air control valve
changed spark plugs
changed the fuel filter
changed the air filter
changed pcv valve
inspected all vacuum lines for leaks and can not find any cracks or worn elbows
i've run high octane gas and fuel injector cleaner many times
i turned it into a shop and they said it was running lean on the passenger side (charged me for a couple hours of labor yet still had no answer to the exact problem)
-i couldn't justify letting them diagnose for another hour, paying them and still not have an answer. they told me they got the code from driving the expo around with the OBD2 plugged in, I've been driving it around ever since with my OBD2 plugged in and no code.

at any rate, i'm thinking having the fuel injectors cleaned. could it be an O2 sensor? maybe a clogged catalytic?

driving me nuts, any help would be great

 

Specifically, what code/codes did they get?

 

Test the fuel pressure and let us know what you're getting for a PSI reading.

 

Lean right side reading - possibly intake gasket or intake manifold cracked??? Just a thought. If they got a code, isn't your check engine light on? Should be if they got a code unless it is a pending code, maybe your reader doesn't do pending codes.