I’ve been getting smoke out of the exhaust and what I think is a burning smell when coming to a complete stop. This only happens usually after going down a hill and low RPMs and a little bit of engine breaking is involved. It’s an auto car so when I say engine breaking I mean like 1,300 rpm or so. And then when I come to a complete stop I get a considerable amount of smoke and odor for about 3 seconds then it stops smoking. Car is a cobra jet setup with no cats. I also noticed that even after my tune was completely smoothed our I ended up eventually getting an check engine code for A/F ratios. Could this be because of a leaky injector? Or because it runs Rick at low RPMs causing it to wash oil off the cylinder walls? If anyone else has had this problem I would love some help.