Just bought a 2008 Hatchback Manual Tranny and it shifts really strange

[way way norcal]

I have been driving manual transmissions since I was a wee lad. This is the strangest shifting vehicle I have ever shifted.
When I am at a stop and ready to go I push in the clutch and I have to give it a fair amount of throttle to keep it from stalling. Normally when you are at a level stop and you push in the clutch as you let out the clutch the rpms are enough to pull forward with very little throttle. If I am at a stop I have to be very careful or it will stall out. I have to ride the clutch and rev into the 1500 rpm range to get to find the sweet spot. And, when I go in reverse I have to give it gas or it will bog down and stall out. When I shift from first to second as I let off gas and push in the clutch the rpms go up slightly and then drop when I release the clutch.
None of these symptoms say to me it is a worn pressure plate. The strangest thing is when the air conditioning is on it actually shifts normally like it should.
Does any one have any idea what on earth is going on here?
I am thinking the idle might be a bit low but I don't know for sure