Pull out the spark plugs, keeping them in order; chances are they're probably gas fouled by now, maybe enough to see which cylinder is misfiring. You may have to put in a fresh set of spark plugs; if it still misfires, try unplugging the Mass Air Flow Sensor first, and see if it runs better.
X2 Slick's comment about the injector o-rings; be sure to check the fuel feed lines as well.
Speaking of EGR, did you remove it and check to see if it is partially stuck open? You might want to try that also.