help my car doesn't pull

[james87gt]

i have an 87 gt with a t-5 with and some modes heres my problem'ssss
1)car runs good for the first 5 minutes and then it has no power and when i try to rev it stumbles i just gave it a tune up cap rotor plugs i did not do the other stuff like wires and pvc and fuel filter cuz i did the like 6 moths ago.
2)after driving the car it steams like crazy out of the breather on the head and when i pull out the dip stick the oil is all up and down it and is really hot.
3)after giving the car gas in any gear and then coming off the gas the car jumps or bogs like some one that can't drive stick was stalling it.
4)this kinda goes with the first probable but it doesn't happen all the time when going from a stop the car stables doesn't really matter rpm even and if i rev it and dump the clutch it stalls out.

my modes are gt40 intake edlebrock aluminum heads 1.6 roller rockers mac long tubes to flowmasters with an off road h pipe no ac no emissions stuff and 355 gears i think forgot some stuff but that's all i can think of now.

any help or tips on what to check for would be the a great help because i am lost and very pissed off