4.0L Acceleration popping ?

[ks172]

Ive have had this problem for almost a year but for the last 3 months it has been getting a lot worse. Need Help ! its driving me insane and cant fine what's causing it.

Problem:

When accelerating with about 1/4 or 1/3 throttle to wide open i hear a bunch of popping from the exhaust (flowmaster 40), it pops between 1500rpms up to 3600rmps than quits and the engine pulls strong to 4800rpms. Its not a loud back fire (like a shotgun), this is a low/deep pitched popping sound like what you would get going down a steep hill in first gear and just tapping the gas a little and the truck starts popping.. that the best way i can think of explaining what it sounds like, but it does it accelerating.

Thing i have done:

3 Sets of Spark Plugs (autolite)
2 Sets of Plug Wires
2 Coil packs (both are within ford spec for Ohm's)
Compression check (within spec)
Vacuum Check (with in spec and steady)
Fuel pressure check (within spec)
Replaced fuel rail to lower intake gasket
Replaced upper intake to fuel rail gasket
Disconnected all three O2 sensors (no change,coloring good,still popping)
Checked MAF (with in Ford Spec Ohm's and Voltage)
2 TPS
Replaced EGR valve and DPFE pressure sensor
Checked oil (normal coloring)
Switched to 89 oct (no change)

I even changed places where I buy my gas and even been dumping Lucas fuel treatment in the tank. Nothing has helped and the OBDII has not given a code.

Other notes: the pops get a little bit louder and more of them when i stress the engine a little, like drive up one of the mountains near me. Also when i drive the truck for about 10 miles and then let it sit for about 20 minutes and start it back up it sound like it has a massive race cam in it. I have to run the engine up to 3k for about 20 seconds for it to quit running rough.

HERES THE KICKER, with a cold engine the truck will run smooth with no popping from starting and running (idel to 4800rpms, or Wide open) for the first 1 to 2 miles of driving than start to pop more and more as the engine warms up

What are your ideas?

O and its a 1995 Super Cab 4.0L with 147xxx miles