Car needs throttle open to start sometimes?

Maybe your O2 sensors need to be replaced. I know my car will kill on me in the cold weather (below 40 degrees) because I am only running one 02 sensor. Another one of those great ideas previous owners do to their cars.

As for pulling up in the 6ks, the power should be lower. These are not lt1 or ls1 engines here. 6k is pretty high...

My car does that sometimes too. Usually when it's hot. But I just floor it and it starts, so no biggie. My combo pulls to about 6600, but it's really singing by then. My guess it that you intake is stopping you from goin any higher.

If you have the stock computer and no chip or anything, the rev limiter is at 6250 anyway, so you're not gonna go past that...the tach is probably off - i've read about some off as much as 1500 rpm.

Pushing the gas when starting actually cuts fuel, so yeah it sounds like you have too much fuel initially and holding the gas cuts fuel allowing the car to start. Consequently, I would assume that maybe your fuel pressure is set too high? What do you have your fuel pressure set at? Maybe back it off a little and see if that helps - that is also assuming you have an Adjustable Fuel Pressure Regulator.