warm start issue and minor miss after installing new heads

I'm starting to loose my mind a little here. I bought a 99 ford ranger 4.0 automatic that I knew had either a leaky head gasket or a cracked head. I got a decent deal but I was hoping it was just a gasket issue buuuut I wasn't so lucky. I could not believe how bad the heads looked after I got them off. cracks between 4 out of the six valves with the exhaust valves sunk in. anyways I bought new complete heads from morana with new head bolts and slapped them on as per Tom's instructions. after I got everything back together and prettied I'm having a warm start issue, a pretty minor miss at idle, and it seems my fuel economy is worse. it ran better with the cracked heads. I need some suggestions because I'm out of ideas

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If your heads were cracked that bad then most likely the 2 upstream O2 sensors are bad from burning coolant in the engine, downstream should be OK, but can also be replaced if mileage is over 250k
Replace 2 upstream for sure

Test vacuum at the intake
To see if exhaust has good flow and general engine condition
Vacuum gauges are still one of the better diagnostic tools to have, $20
Info on tests here: http://www.gregsengine.com/using-a-vacuum-gauge.html

Light misfires are idle can be dirty injector tips, can of Seafoam in the gas tank will clean them.

Clean MAF sensor every year on the 4.0l Rangers


All fuel injection computers have a "Clear Flooded engine" routine
For Fords and most others it is this
Turn the key on
Press gas pedal down to the floor and hold it down all the way
Try to start the engine
It should NOT start, it should not even fire

Whats happening:
Key on boots up computer
Gas pedal to the floor sends 4.5volts from Throttle position sensor(TPS) to computer
When computer sees the 4.5v from TPS and RPMs are 0, it will turn off the fuel injectors, but leave Spark on

So cranking engine without injectors on and throttle wide open will dry out a flooded engine, Clear Flooded Engine

I use this every morning on my high mile 4.0l, I pump oil thru the engine before allowing it to start.

As soon as you release the gas pedal the computer will start fuel injectors, even while still cranking.

So do this test for your Warm Start issue, maybe you have a leaking injector, and its flooding the engine.
Gasoline would evaporate after engine sat for 4 to 8 hours so wouldn't effect cold starts
It would also explain lower MPG but so would failing O2 sensors

Check your oil also and see if you have any evidence of fuel in it.

Did you change your plugs? I had a V10 torn down at work for heads and when I put it all back together, it ran like a pile of crap. It turns out that a coil had gone bad. Luck of the draw..


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