BAD MPG AND CANT PULL!? HELP
 

So i am getting like 12 maybe 13 city right now!? shouldnt i be getting like 18 or close to? what could it be? injectors? And i did have a remote start put in a few years back and the guys did it wrong and it ended up screwing things up. like my vp, alternator, and a few other little thins i cant remeber. could it have screwed up the computer and its not working right now? oh also i am lacking in power. i had a fifth wheel that it used to tow no problem and now it has major trouble. I even had a tough time will like a 7000lbs boat, and it might not have even been that. Please anything helps i want my old truck back. oh and everything is stock, other then its strait piped.

Thanks John

Codes? do you have gauges? Is it smoking; if so what color? Could be bunch of things....

Many things to be checked,fuel filter, lift pump pressure, codes,apps,leaks in boost system,if your auto,lockup dragging brakes

It is an auto. Has no codes that i know of, ill check tomorrow. And it will smoke a little when its really cold out buts its white smoke and only does it when its first started then goes away. How do i check for dragging brakes or a leak in the boost system?
Thanks guys.

Did you hook it up to a code reader, or just no check engine light?

Here is a link to the boost tester: https://www.dieselbombers.com/5-9l-2...ak-tester.html

It is probably not that as you say it doesn't smoke. I'm betting tranny or fuel. Get some gauges so you know that you have good fuel pressure. I never had an auto so I can't help you with the tranny unless you want to do a manual swap.

Dragging brakes you should feel and/or hear. Coast it down a slight hill applying the brakes and letting off. If it rolls smoothly when you let off; you are good. If not; check the brakes.

IMO, an upgraded lift pump is a must on these trucks. I had 1-3PSI of fuel pressure when I got my 99 with a supposed brand new stock lift pump. After the air dog; It doesn't go under 12PSI no matter how hard I run it. It's cheap insurance because VP44s are not cheap or easy to replace. I want to keep mine around as long as possible.

You could try resetting your apps and checking your fuel filter in the mean time. There is an article on here somewhere about how to do it. It made a world of difference in my truck. Just search for apps and you should find it. Good luck!

Could be a timing issue with the vp44, = bad mpg, white smoke, low power.

Check codes and lift pump pressure.

Check lift pump pressure for sure. Poor fuel supply to the injection pump can cause many issues. Poor MPG, low power, smoke, and eventually a failed VP44.

I agree with RAW. Check your fuel pressure low lift pump pressures cause hard starting, poor fuel economy, poor performance (Power) and quick damage to the injection pump. If you don't have a low pressure warning system for your lift pump (gauge, light) you need one. Second biggest problem is boots on the intake check your boots from the turbo through the cooler to the intake on the engine make sure nothing has come loose or slid apart (it happens more often than you think). Just because the boots look good doesn't mean they aren't delaminating with age either. The big power loss your describing with the resulting decrease of fuel economy sounds fueling related though (i.e. lift pump, filter, injectors). Have you had any recent work done on the truck or is this a gradual/sudden problem?