she randomly wants to be lazy...

87 GT 5.0 HO, 5 speed, MAF converted - after about 2-5 min of driving it will start to backfire through the intake, buck, and stumble. If I floor it, she fires off, and goes well. once it's warmed up a bit (with barely any indication above 130 on temp.) it will be ok, unless I am going up a hill/ heavier load in 5th, then it lacks power and stumbles and pops again. once on a level plane again its ok. messed with timing, spout out! - 10, ok, 14 is better, but still does it. I am currently running low oct. gas, and have pulled timing back to 11, or 12. TPS appears to be operating properly and within range. - set to .862 (yes I have a fluke.)

codes - 82, and 85. canister is out. not noticing any vacuum leaks. it does hunt for idle within 150rpms or so of 1000. the passenger side of the firewall where all the solenoids and vacuum mess is seems a bit garbled by PO, but from what I can see it looks to all be sealed.

it runs great, and goes well when it is not doing this condition, be it cruising or running through the gears! its almost like a switch the way it comes and goes.

when trying to accelerate normally while its acting up - it sounds and feels like I can feel every piston hit, and you can hear distinct deep da-da-da-da-da-da-da of an exhaust note as it slowly accelerates, instead of the smooth bwaaaaaaaaa.......

only running catless X pipe, MAF conversion, and smog delete.

plugs and wires are new from when I installed the engine (rebuilt) about 3k miles ago. MSD cap, rotor and wires. I think the plugs are autolite's.

canister was removed prior to my having the car, not sure about vacuum hose location/route.

when I first start up it goes to ~1500, then will come down and stay around 1000.

5th, anywhere between 1200-1800RPM.

I notice that when its acting up within 20-80% throttle range if I floor it, it clears out, and runs fine for a few seconds within that range, then goes back to being crappy.

how much of an affect like this would a bad temp sensor have on this? I would have said, oh its o2's since it does it once warm, but it would click out of the messy running, and go great after that which kinda drops that thought. its not fan wash, not consistent problems. fuel pump is brand new.