Low RPMs
 

Im near the end of my summer project,

My car is almost restored completly (After 4K pumped into it) but I'm down to the last problem.

My RPMs are low,

To give you the overview:

My base idle speed is around 300.

If I turn my AC on, my RPMs drop around 100 and rattles a bunch (Expected)

My car will not go past 3500 RPMs (In gear or in Neutral)

My air flow stock gauge will max out without a problem, but I'm afraid of burning out my turbo on my car do to trying to build up RPMs to drive on the interstate.

Any ideas what may be causing this?

Car: 97 Mitsubishi Eclipse Spyder GST

How does it sound when its idling? Is it smooth at 300 or rough?

Its pretty smooth, stays that way unless I turn the ac on

Anyone have any ideas? I considered having it smoked to check for leaks