I have exhaust coming from the middle of the Jeep

Hi,
Likely an exhaust heat shield. When the SUV is cold - after sitting for 4+ hours - crawl under the vehicle and see if any of the shields are loose that cover the exhaust pipes. If they are you can use sheet metal screws screwed into the shield and against the exhaust pipeto 'wedge' the shield so it doesn't move.

GL,
Td

Drop the tank remove all fuel replace the filter and fill with fresh gas

run a quality injector through the system as the injectors may not be operating properly

Sounds like you have a bad head gasket.

check the O2 sensors in the exhaust manifold with a automotive meter not a code reader ,then trade it in for a diesel manual version as these are impressive but 4.7 litre gas guzler at our petrol prices about 10 dollars a gallon in the -uk and around 7/8 dollars here in spain this vehicle you couldnt give away here

Chances are one of your exhaust pipes is hitting something or a shield is loose. Easy to check, just try and move the exhaust system and see if it contacts anything, then start it up and track the noise to it's source. DON'T touch the pipes when it's running or has just been running. THEY ARE VERY HOT!!

I have seen fuel pressure issues cause this. Fuel filter, or fuel pump. However, I have also seen the catalytic converter cause this issue. The honeycomb, located inside the catalytic converter, breaks up and will block the exhaust when you accelerate. Engine power is lost, until you let off the gas and let it idle. Then, the chunk falls down from the exhaust port, and it runs fine again. Until you get on the gas and increase the velocity of the exhaust, and the chunk blocks the exhaust gasses again. Good luck

I have the same Jeep and same problem. The engine was running rough. The Jeep dealer fixed a vacum problem in the manifold and they then decarbonized and cleaned the fuel injectors. After these repairs the idle problem began, it would spike to 2000 rpm while sitting at idle, sometimes it would slowly come down, sometimes I would have to tap the accelerator. I took it back in and they then replaced the throttle motor and reprogrammed the PCM (Power Control Module?) Still same problem. Now they suspect a another vacuum leak and I am taking it back in on Tuesday, will let you know what happens, $ 1,300 so far.

Could have a bad map sensor. The Map sensor is located on the throttle body. I have seen countless Jepp that start blowing black smoke when they go bad. That would be a good starting place.

dont know what you mean about "a bent pipe coming off the headers" it sounds to me the exhaust gas cannot escape out of the system past the CAT, is there any exhaust gas coming out of tailpipe ? put your hand there to feel the pressure whilst someone else revs up, if little or no pressure just disconnect the back box (if possible) this is the coldest part of the system and all the exhaust water ends up there, baffles drop and block outlet. good luck