I'm not sure what exactly is going wrong here. I'm using the X-Checklist found in the link below. I've seen plenty of people use this checklist before and have no problems. I've followed all of the preflight procedures leading to engine start, but when I try to start the engines, they don't want to start.
Every time I start the engines, once they reach 25% N2 I set the Fuel Control switches to Run. They begin to start up but then die back down to around 25% N2, and then fluctuate up and down every few seconds.