question to anyone with experience with 99's V6 4.2. just had intake gaskets replaced, still not running right. Tends to buck a bit when I go to accelerate from a stop. Replaced VMV, still not the problem, thinking it may be the charcoal canister. any other suggestions ?

 

is there a CEL on or anything?

 

not at the time, but it recently did come on. Lean codes p171&174, banks one&two, have had all obvious vacuum lines done, Mass air flow sensor has been replaced, I think now it's both air and fuel. Your thoughts on it. Thank you

 

no broken vacuum or PCV hoses? intake manifold torqued down correctly? intake tube loose on throttle body?

 

Intake gasket was done by Ford, have checked those, did not think it was these. All other vac lines have been replaced. Rubber ones that is. Have one plastic one running from VMV, and one from EGR. Will check those you suggested and will get back to you. Thank you

 

The codes 171/174 tells you about all you need to know.
The Air Fuel relationship is upset. This causes drivability issues because it's not a normal condition.
There is still an air leak as detected by the OX sensors for both banks as excess air in the exhaust.
A verify of the fuel tables will show this.
It would be nice if mechanics would use there test equipment to look at these things instead of guessing both before and after the work is done.
Good luck..

 

Been replacing vacuum hoses the last couple of yrs because of lean codes. Something caused the intake gasket to go other than age of vehicle. Did find out that this V6 4.2 is notorious for the gasket to be replaced. Your right that these mechanics need to use these tools to get to the root of the problem, unless it was meant to keep bringing me back so they can have access to my bank account, LOL.

 

Was able to check PCV, there is vacuum there, haven't checked torque on intake, intake tube is tight, unless its worn, tube going from VMV to intake seems like its collapsing a bit. I don't think it's supposed to b doing that. Acts like there is blockage coming from the rear fuel system. Thank you