had a distributor go out, after the dealership replaced it, I have some issues:
low mileage
power loss
rough idle
low/inconsistant idle
truck dies when motor is cold
it also seems as though the brakes a a bit softer, may be conected?

 

Dealerships have gone to crap. They're more interested in selling. Go figure.
Appears one of the dumb a$$ "mechanics" replaced the distributor. Take it back and raise he!!. No excuse for that crap coming from the dealer. If they screw with you, call your local TV station and tell them you have a story for them.

 

check for a vaccuum leak.

 

Idle is very easy to adjust. It should be at 950 rpm's. It also sounds like your timing is way off. take it back and make them fix it right.

 

800 rpm(+/- 50 rpm) is the correct idle setting for a 3VZE.

I'm always suprised that nobody ever gets that right. Oh well, gives me something to do correcting them.

Oh, about your issue. I would also check for vacuum leaks very carefully. Paying close attention to the vac hose that goes to the brake booster. That would soften your brakes if it was leaking(seems counter-intuitive, but trust me), as well as cause the rest of your symptoms.

 

But if you want to have a go at it, check the timing first. If the set the timing incorrectly it would result in all of the above.