Hey guys hows it goin???

I have an issue!

my budy's 99 Ford ranger 4.0 V6.

Truck history: I replaced plugs and wires this spring

He brought it to me a couple weeks ago when the alternator died. I replaced that along with the Serp belt, air filter and the MAF sensor.

He drove it for a week or so and brought it back to me saying it still STRUGGLES. Whenever you step on the gas pedal more than a little bit the engine studders....the hole truck bucks and the shifter shakes back and forth like crazzy from the vibration. Once it gets up to higher RPM it seems to smooth out a small amount.

It had the codes, P0171 and 0174, lean banks 1 & 2. The truck also leaked coolant.

I replaced the lower & upper intake manifold gaskets, as well as the fuel rail gasket.(he had the fuel filter done a couple thousand miles ago) I cleaned out the throttle body with carb cleaner, and the vacuum hoses. I checked every vacuum hose by taking it off and blowing through it and plugging the end with my finger...they were all tight, no leaks. I checked resistance of each Fuel injector, IIRC they where all around 14 ?

I have no idea where else to look.... Ideas anyone??? I'm baffled....

 

anyone??