Thanks in advance for any assistance. I have a 2006 Dodge Grand Caravan SXT with 260k miles. Yesterday it starting having trouble shifting gears. It's very slow to go and right as I get to about 30mpg it drastically slows acceleration and the rpms get up to about 3k. I have to let off the gas a couple of times to get it to shift into the next gear. It's not just this gear, but it's most noticeable at that speed. It almost feels like I have to push the pedal to the floor to get a response at higher speeds, as well. There has always been a slight smell under the hood because it does leak oil, but since yesterday this smell has been greatly amplified and as I opened the hood upon getting home today it was smoking a little from under the front part of the engine. The latches on the floor that the fold in rear seats attach to are so hot you can't even touch them, which makes me think something underneath the car is heating up abnormally high. I used a code reader and got 5 codes, but two of them repeated, so 3 unique codes.
p0404 egr position sensor performance (repeats twice)
p0420 catalyst efficiency bank 1 / catalyst 1/1 efficiency (repeats twice)
p0406 egr position sensor circuit high
I read that one of these codes has to do with the catalytic converter, and that the cat converter can cause issues with transmission shifting. The article I read says that this issue can cause overheating which in turn can cause the transmission fluid to overheat and cause these issues. I called a repair shop and he immediately recommended replacing the transmission. I'm really trying to be optimistic about this and hoping that it can be something besides a $2000 repair. Any ideas?

Thanks in advance for any assistance. My main goal is to get opinions on what to eliminate/rule out in this situation. I have an 06 Grand Caravan SXT and yesterday it starting have issues shifting gears. Once I get to about 30MPH the acceleration stops and the rpm's go up to about 3k. I have to let off of the gas a few times in order to get it into the next gear. Once it's in gear it runs ok, but it's just having trouble getting there. The normal oil leak smell under the hood got much worse, as well. Also, the metal latches on the floor that the rear seats attach to got too hot too touch, which makes me think something was running very hot under the van. I was told to check the fluid, and it's normal. It's pulling 3 unique codes. p0404 egr position sensor. p0420 catalyst efficiency bank 1 (catalyst 1/1 efficiency). p0406 egr position sensor circuit high.
I read that a bad cat converter can cause transmission issues, but that the way to know is if it doesn't accelerate once actually shifting gears. Since it does, it sounds like that might not be the issue. Since this is my only real transportation, I'm really hoping it's something more simple than a full transmission replacement. Does anyone have any suggestions as to some steps I can take to rule some other things out? I'd be more than happy to repair some other possible causes in hopes they are the culprit. Where should I start? What are you thoughts on if this is transmission?