I have robbed this forum of useful information for a while, and decided to post the results of fixing my truck issues.
I have a Dakota Quad cab 4.7L 2WD. It started, as many have experienced with surging at idle. I would pull the IAC and clean it. This would fix the problem for a while. I did this quite a few times until it would only fix it for a day or two. I then replaced the IAC. This fixed the problem for a short while, but then the surging at idle came back. Eventually the surging started happening at highway speeds. Even with the cruise control on, it would surge, and even down shift sometimes. The truck seemed to be running a little rough, and I average about 15mpg.
Sometimes while in park, the truck would idle near 2000rpms. I would have to wait a while for it to come down to put it in drive. Pain. Annoying.
After researching on this forum, I decided to change the TPS. What a difference. I have only put 20 city miles on it since the change, but it is very noticeable. No surging when started. Idles nice and low where I remember it being in the good old days. Drives smoother, and has better throttle response.
WOW.
A little bit of the results might be in my head, having changed a part, but it is definitely running better.
I will give it some more time and let you know what the results are for mileage and highway driving.
Thanks everyone for posting on here. This forum has helped me make my truck last longer, which is very important today.

BTW, Throttle Position Sensor was $43.00 with tax here in Florida. Cheap and very easy fix. Wish i had done it a while ago.

Now on to the other truck issues. Exhaust leak under hood.

 

Just curious how your exhaust leak turns out - any chance it's a bolt? I had an exhaust bolt break on mine and it was a bear to get to! I had it fixed because I didn't have the time to mess with it myself, but the mechanic had a tough time getting to it and pulling the broken one out - ended up drilling it out and putting a heli-coil in it, and still it was a pain.

Interesting about the TPS - I have had an interesting surge lately in my truck and I'm not sure if it's just a nuisance or something I should look into. Going downhill (at highway speeds) I drop it into neutral and the RPM's flux between about 700 and 1000. Ram air driving the fan and somehow affecting the idle? Something else obvious to everyone but me? Anyone else have the issue? Mine idles fine at a standstill. It's not anything that I think is a big problem but it's a bit odd.
Appreciate all the info on here.
Patrick

 

I took my truck to my usual exhast place to check the leak. He said he wouldn't touch it as it required bolts be removed that will most likely break, and he cant afford to be doing the drill outs etc. He suggested it is a dealer job. I found a mechanic who worked at Dodge, and as soon as I can arrange to get it there for a day, he will do it. Apparently it is common, and he stocks the gaskets and bolts for the job.

Drove my truck on the interstate tonight. Cruise control too. Excellent. The TPS has really solved several of my problems.

Your symptoms are similar to what mine were, but a different scenario. Good luck, and I will post about the exhaust.

 

yea I had the same TPS issue on my 2004 Dakota and had to replace it , but haven't yet replaced the IAC , but considering it as the truck still idles a bit rough

 

I have a 2004 dakota with the 4.7 V8 and when my TPS was bad mine would actually die (kind of like a stall) it would flux and then just die when at idle too long (which was about a few min , some times 5 or 10 min) replacing the TPS did fix this and I also cleaned the IAC and am thinking of replacing that too as I still have a bit of a rough idle. TPS will only run you about $40 , but I think IAC may be a bit more. It's worth a shot to try replacing the TPS and the IAC as well if you want.