I have a 1995 GMC Sonoma, v-6. About a week ago I noticed my rear exhaust pipe had broken and was hanging down beyond the muffler. I drove it a couple of days until I could get it repaired. Before the repair day, I noticed that the truck was starting to run rough. The exhaust reapir was taken care of, and now the truck is running very rough and using gas much faster (normally 20 MPG, now about 15). Is the exhaust problem related or not? What could it be? Less than two weeks ago it was still getting 20 MPG