Fuel Injector/Pump?

I have a 2001 GC Limited with 55,000 mi. It has Auto Tranny, 4-wheel drive with a V-8 engine. As I was drving down the highway (60mph) it started to shudder and white smoke billowed from the exhaust along with odor. No warning lights were on and all guages were reading appropriately. I reduced my speed until I reached my destination (2 mi) and shut it off. I was able to start it again, but it took a long time for it to turn over. I proceeded at a slow speed and then the MIL came on. I had it checked at a local garage and they said the only thing it said when it was scanned was that it was misfiring on two cylinders. He is guessing it is the fuel injector/pump, but is hesitant to try it since it is really spendy. Are there any other possiblities before I pursue this course of action? Thank you for your help!