So I've been fiddling with this thing for months. Basically, the idle is rougher than i'd like it to be. Power seems low, and the transmission shifts as if it is not tuned to the engine it's attached to. This all happens when the engine goes into closed loop. On occasion It will start idling very poorly and hesitating/stalling off the line. Here is a list of things that I have done.

Spark plugs (h9dco)
injectors (genuine bosch) + seals
cap and rotor
Head gasket
rear muffler (rusted out, unrelated)
o2 sensor
adjusted duty cycle (tamper ball was missing)
air filter
cooling system flush
Fuel Filter

When it goes in to hesitation mode, The symptoms are exactly as If I held the EGR open. Vacuum decreases, Idle is bad, but at higher revs it is fine. I thought about checking the EGR for leaks, but I figured before I went and broke studs off, I'd ask first. The diapragm is fine and it snaps shut like its supposed to.

Fuel pressure is nice and high, around 80 PSI. Vaccum is around 15 when it is not in hesitation mode. I haven't gotten a good MPG reading since changing the injectors, but intown mileage is abysmal. around 210 miles per tank . Highway I got almost 27 mpg. I can't find any vaccum leaks anywhere. Anything else I do will be shotgun replacing, and I don't want to do that. What should I check out next? I really like this car.

edit: It starts as if there is air bubbles in the fuel lines or something. sometimes it start,die,starts. sometimes I just have to crank through some dead spots.