Running lean and chugging and pissing me off honestly................................

[parson2008]

my 93 ranger 4.0 is running lean,i recently completely rebuilt the top end (heads, valve job, rockers, injectors). now after all that my engine is running lean. when i start it up it idles good and temp is normal but when i go to drive it the temp slowly goes up to about halfway. the engine is running lean i can see that on my air fuel guage and it never did that before i rebuilt it. also put in new plugs, wires, air filter, water pump radiator. i am picking up new o2 sensors tomorrow also a new MAF sensor. but does anyone have any clue why it would just lean out?

one more thing is when i first start it and start driving it chokes or misfires but when i stomp on it, it does not. but after a little while of driving it stops.

 

[Sasquatch_Ryda]

Could be a vacuum leak/intake gaskets leaking....a number of possibilities...

 

[therangerviking]

did you gap the plugs or at least check the gaps before the tune

 

[01_ranger_4x4]

Could be a vacuum leak/intake gaskets leaking....a number of possibilities...

X2, vacuum leak would be the first thing I would suspect.

 

[parson2008]

checked for leaks... nothing

 

[cookiemonster]

Fuel pressure regulator?.....wanna sell your truck, its beautiful i love it!