P0089 - Fuel pressue regulator malfunction & P0300 Cylinder Malfunction.

What is your question?

Unsure how this relates, but headed out of town, stopped to fill up using E85. Still had 1/4 of 89 oct in the tank. 70 miles later engine light comes on and car starts smoking. Dealer says #4 injector is stuck open & #4 plugs is fouled. Dealer replaced #4 injector & all plugs. Dealer says #3 injector is now dumping fuel. What else could cause this problem? I don.t want to pay dealer costs to replace each injector just to find out is was caused by something else. I'm not familiar with direct injection, but this sounds like it'd have some to do with the engine management system?