Here's one for you guys. I replaced the engine out of my 82 Toy with a 85 4-Runner 22R in October. I recently developed a popping/back firing sound out of my exhaust when I down shift. This was just after my temperture gauge in my dash went f**cked. I figured my fuel mixture was high so I backed it off a bit, but that didn't help. So I figured that it might be in the carb so I rebuilt it last week. Still no better. I replaced my muffler yesterday hoping that maybe I wasn't getting enough back pressure, but still no improvement. The one thing I did figure out is that the old engine didn't have an EGR system where as the new one does. Any ideas on how to by pass the EGR? Is it really necessary? Please help!!!