I replaced the rollover valve and it did not help the situation.
I don't have to be cornering for this to happen. In fact, it happened three weeks ago when I was driving around 30MPH, slow, steady throttle. My mechanic said it could be a ground issue, so I let him go through the car and check and tighten every ground wire (they actually have a procedure for this, takes about 3 1/2 hours). It didn't do it for about 300 miles, but did it just today under hard acceleration. However, instead of cutting out for about a second like all the other times, it cut out for around five seconds.
I actually hope it gets worse so it will point itself to the issue and I can fix it.