Emissions problem?

alright i blew a head gasket. which immediately forced water into the oil and caused the dreaded white boiling of the oil which got into everything. while the head gasket was blown the car lost power and smoked from the exhaust. it idled like it was trying to beat itself to death. so i got it home.

the head gasket is fixed. the oil is changed.

i take it to autozone to get a DTC reading and see what else is messed up...
reads out a P0300 random misfire. so i change the wires and spark plugs.

reads out an egr code so i take it off and clean it? then replace the gasket.

reads out a P0171 code lean fuel detected. bank one ( oxygen sensor one)

ok egr code is now gone.

figured out that the misfire is caused by the lean fuel mix

but.... car still has no power. still smokes. burns oil

these are the driving symptoms:

car accelerates ok but no power. it will not maintain speed when you level off. it shakes and bogs down then if you accelerate it smokes and then goes again regains some power at high rpm. bogs down when you try to level off at one speed. when stopped it idles hard when in drive but idles fine in park or neutral.

this is what i thought but have been wronge so far.
1) clogged fuel line
2) bad egr valve
3) vaccuum leak
4) bad catalytic converter or clogged
5) bad MAP sensor (just got it replaced)

I cant think of anything else to check and the haynes repair manuel is also out of ideas....

HELP!?

alright i figured it out.

ok it was a bad O2 sensor
aparently it wasn't dead but was sending a constant lean signal to the PCM which in turn caused the PCM to try to compensate by enriching the fuel content and spending hella gas also flooding the engine causing the burning oil and the smoke.

new O2 no more misfire. no more check engine