We have a 97 Ext cab 4x4 Dakota 3.9 auto with 267K. This is our run to the dump, haul the camper and back up bad weather driver. It took 18 months to put the last 3K miles on her. I had noticed decreasing performance and a compression test revealed...
1) 125/140 2) 120/140 3) 130/145
4) 100/120 5) 95/110 6) 110/120
Now we have picked up a new camper, going from a 1600 Lb popup (loaded) to a 3200 Lb Hybrid Camper, Dry weight, guessing up to 4500 Lb total. The truck handles the camper surprisingly well, but even small hills kill it, especialy at highway speeds. So now I'm facing...

1) New Truck...not fesable at this time but keeping an eye open for a deal .
2) find a used 3.9 and drop it in. cheapest "fix". $300-500
3) go to a 5.2, concerns about trans & rearend @ 267K and more money we dont have.
4) keep pushing untill???? Most trips are within 2 hours of the house, figure 6-8 a year.

So what would you do? any other ideas?