98 24 valve dead pedal and transmission issues

So I bought a truck yesterday from an older couple that had had it since new 98 Dodge Ram 2500 24 valve cummins with 190,000 miles on it. I got the truck for a really good price the ad did say it had an intermediate issue of losing power. I test drove the truck about 16 miles and I did experience the power loss, driving down the road everything would be acting fine and all of a sudden the truck would lose power kind of like it was running out of fuel. The further you push the pedal the more the engine would bog and slow down. I let off of the pedal and the truck picked right back up and felt fine. Then went back paid for the truck started to head home I stopped at a stop sign went to take off and the truck wouldn't shift out of first gear. I stopped on the side of the road and did some looking around online found some information that said to check the seven wire plug on top of the transmission, I unplugged it cleaned it off plugged it back in. I got in started the truck crossed my fingers and took off and the transmission seemed to shift just fine. I had a couple hour drive home and these issues kept coming in and out during my drive. When I got closer to home it started to get dark so I turned my headlights on and realized sometimes the headlights would get brighter and dimmer. A friend of mine told me to look into dead pedal and that sounds like it matches the power loss issue but as far as I know not the transmission problem. But then I do realize that the tps needs to be in the right parameters to work correctly and the voltage going up and down could effect this. This morning when I went to start the truck back up it did blow a little white smoke. The truck is all original absolutely nothing has been altered or changed, I just don't know if these 3 issues could have a common solution or if I'm dealing with 3 separate things and what I should tackle first.

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If your headlights are surging you need to get that handled. Battery, cables, ground point, alternator. The low voltage can be doing some crazy things with fuel pressure and sensors. I would tackle that first as its really the easiest to rule out and cheapest.

The throttle problem can come from a bad fuel filter or if there is a water trap that needs to be cleaned out. The filter might allow enough fuel to idle and some power, but under high demand might not have the flow to push enough fuel and the truck will fall on its face, this could also be the fuel pump. Get the scan tool plugged in and reading live data and look at low pressure fuel pump pressure and duty cycle. This will get you in the right direction.

As for the transmission, thats where my knowledge runs out.

I would clean the connection at the pcm. You could remove the pan and take a look but It doesn't sound like a transmission issue I have heard of. That it goes away and comes back. Although I have heard of something similar with a beat drum seal. I would take listen to the torque converter as there problematic. At 190k has it been rebuilt before?
I almost forgot no check engine codes? Codes will say a lot. I bought a obdII Bluetooth thing on ebay for less than 20$ then I used my cell phone with a free app and it does everything my old 120$ one did.