some minor issues I need help diagnosing - '87 V20

[werewolfx13]

So, with my truck down with the melted ignition switch harness without a known cause for the meltdown (and plans to convert it to 4wd w/ a new harness anyway), I've borrowed my dad's '87 V20 w/ home built (sorta) flatbed. This truck was owned by a pig farmer from early in 1987 til sometime in 2007. Its a tbi350/th400/np208/non floating 14 bolt rear/10 bolt front. Dual exhaust, but the drivers side is off just before the cat. The truck runs great til it just starts to get warmed up, then it stumbles horribly on takeoff unless you either idle off, or slam on it. Transmission shifts fine, transfer case is the smoothest operating NP case I've ever operated. Has new plugs and wires, I think one of the guys that works for my dad replaced the cap as well, but I need to double check that. It "feels" like a fuel problem to me, but I haven't had time to give it a looking over (its been miserably cold lately, my indoor/outdoor thermometer says -3 right now) It does it the same regardless of how full or low the fuel tank is, so I'm wondering what on a TBI 350 would cause the problem. Any ideas would be much appreciated. My first thought was o2 sensor, because i KNOW thats not been changed.

[Layne]

Fuel filter maybe??? Any DTCs?

[Irish_Alley]

tps could be a problem

[Irish_Alley]

or egr. or even due to the fact your exhaust is not compleat causing not enough back pressure on that side throwing off the egr

[VileZambonie]

If you have an exhaust leak and it only does it when it warms up the O2 sensor is probably reading way off dur to the exhaust leak. Fix that first.

[werewolfx13]

Thanks for the replies, while I was crawling around under the truck night before last to put my magnetic block heater on the oil pan, I looked around for the O2 sensor, but couldn't find it in the dark, if I can find a dry spot on pavement to park it, I'm going to slip under again today in the daylight and see if I can spot it. The exhaust on the truck has obviously been changed from the manifolds back. There is a partially mostly melted sensor on the very front end of the drivers side exhaust manifold, any ideas what that could be? the hex shoulder looks like an O2 sensor, but there is not enough left of the rest of the sensor for me to determine what it is. If I can't crawl under the truck today, I'll take a few pics of the mystery sensor and of the rest of the engine bay. I THINK the EGR valve has been removed and covered, but I'll double check that today as well. The smog pump is disconnected, as are many of the related components. Fuel filter was also replaced I think, but I'll ask about that.

[Captkaos]

The O2 is mounted on the bottom of the manifold.

[Irish_Alley]

well if its been removed i would all most bet its the exhaust (big) leak thats the problem

[Marc]

I've seen a bad distributor pickup and a worn distributor bushing cause some pretty odd stalling issues, and if the coolant temperature sensor is out of range it could be overfuelling the engine. Check the oil and see if it is thin and gassy smelling.

[werewolfx13]

The oil is definitely not thin, I check it religiously, and its as thick as 15w40 rotella- T ever is in the winter.