I usually get about 40lbs of boost and now im getting 25 if that. Its seems like 1st and possibly 2nd gear are gone but also takes time to boost. The truck has not much power. Instead of giving it gas and it goes, it is very slow in low gears. I thought maybe a boost leak but cant see anything and not sure how to test. I have tranny fluid and its not like the tranny is slipping. Its actually a built tranny with only about 8K miles on it so i dont think thats the problem. Any input would help. thanks
its an 05' auto.
And yes i did put the chip back to stock and the only difference is that i dont blow near as much smoke.

 

If you do a search there are a couple posts giving info on how to build an inexpensive tool to pressurize the intercooler system. Basically what you do is put a plug in the inlet side of the turbo and pressurize the system with a regulated amount of air pressure.......then what I do is spray a soapy water solution on all the joints and look for air bubbles.....a lot of times if there is a leak you will find a boot clamp or 2 that has worked itself loose and just needs tightened....don't forget to look at the intercooler itself sometimes they will split a seem that can be hard to see.

 

This may sound dumb but when was the last time you changed the fuel filter.

 

Any engine codes? Sounds like the turbo is runing in safe mode. This happens if boost sensor is not sending or receiveing proper voltage. Look for bad wire close to sensor and turbo.

 

You say 1st and second may be gone, then you say it is slow in the low gears?? Is it not starting out in 1st? Limp home mode?
Clear all codes and drive it. If it comes back it is limp mode. What are the codes?
You need to find a trans guy.
Even with a built trans the electronics can fail in the trans.
The more you drive it like this the higher possibilty of hurting the trans.

 

I would also take a look to see if the turbo waste gate is stuck open.