00 Ranger idle problem

[TRACTOR MAN]

I'm working on a 2000 Ranger with bad idle. Codes read have been o-2 sensor,MAF, misfire on #4. The idle sensor checked okay, air temp sensor okay. I cleaned the MAF 3 times with no improvement. I turned the screw at the butterfly to increase the idle speed which caused the engine to run almost perfect at a slightly faster idle. After driving it a few miles the engine returned to it's fomer condition and almost died at idle.
Have been told by a Ford shop that compression on #4 was low. I will check it myself soon. Could be blown head gasket?? No water in the oil-replaced the water pump because it was leaking. Also replaced the alternator at the same time because it was dead.
Could be a fuel pressure reg? Will check again for vacum leak-none found yet.
Can anyone help?

[dtek]

ya check your fuel filter an pump pressure eithrer one can give you these symptoms anpull your injectors an test them a plugged injectors has similar symptoms also check electronis cap rotor etc a bad cap when cold will runn normal but as engine warms the heat wiill cuase a crack to get bigger an cuase an indiference in idle but still run down the road usaly a bit rough though good luck