1989 Chrysler TC Low Boost Issues

[gtristan18]

So last week I decided to buy a Digital Boost Gauge. After installing the boost gauge I found out that my car had only been hitting 4 pounds of boost this whole time. I was told that stock it was supposed to be on 11 pounds.

I purchased a vacuum block and made some adjustments to the vacuum line. I got my idle vacuum to be about -15 to -16 (it goes back and forth.) I was told they should be at -18. I also did the check to see if the wastegate was stuck by attaching the waste gate vacuum line directly to intake manifold, the test said I should hit 5 pounds and I did, so I can rule out wastegate.

And just about an hour ago I ran piping straight from the turbo to the throttle body to see if the intercooler was bad and still had 4 pounds of boost. So I can also rule out a bad intercooler.

I am now trying to tackle this issue. I just purchased a 13 port vacuum manifold and 40ft of vacuum line. I plan to redo all of the vacuum line in the engine bay (since its from 1989 and could be cracked or damaged.)

I was wondering if there is anything else I should be checking or trying. I was also informed that maybe I have a faulty MAP sensor. And I also plan to redo timing as I am running really rich for some odd reason even though the timing is pretty spot on as far as idle RPM.

Thanks!

----- EDIT -----

I would also like to add I also purchased a Grainger Valve and installed that as well. I set the Grainger Valve to be fully open so max amount of boost and I'm still only hitting 4 pounds of boost. And the boost doesn't come on quick either. It takes about 5500 RPM just to get 4 pounds.