Yeah...a lot of the OP's concern has to do with his confidence in the truck after all the trouble he has had.
If it were me, I don't think any amount of aftermarket $ would give me a high enough level of confidence, with a vehicle that has been so much trouble, to take my Family on extended trips.
We tend to keep our vehicle for 10 yrs min...but when they get unreliable...it is time to replace them...no matter how old/new they are.
Right now we have one 7 yr old truck, and one 14 yr old car. Both dependable.
The PIA factor is too great when you can't trust your vehicle.
When one of these gets shaky...it is gone.
B