Just wondering what causes the boost gauge to read -23 at idle? when i press the pedal it cuts off between 1000 to 2000 rpm then it revs normally and dies after idle? Also, the car is throwing throttle module and throttle relay codes.

here is my mods:
greddy tt
utec
stock engine

Any thoughts would be appreciated

 

The engine draws vacuum under idle, that is why it reads vacuum (negative pressure)

As for your other problems, I don't understand what your question is.

 

The engine is drawing vacuum, a negative reading at idle is perfectly normal. The other issues sound like it could be tune related - what has been done to the UTEC? What are the codes?

 

-23 sounds a little bit high, but nothing to be too worried about. i am at -15 iirc with cams and idle at 1000rpm. if you were reading it in a cold start (raised idle) then that would be a normal number.
try replacing the throttle relay if you are getting those codes. or, wiggle it around a little.