Ok I got a 99 jimmy that I did get a code of 2 heater sensors being bad or O2 sensors.But will this cause my jimmy to start running rough and the smell of carbon?Once I rev it up it balances out.Now former owner had to have emission checks and I sometimes feel this.messes the converter up but probaly not but it sometimes puts out a real fine black smoke out of tail pipe like its running to Rich.Now could these sensors be the real problem ?and what else could it.be?Would a.bad fuel pump which.mine is bad be causing it?And last when I first start it especially with it parked uphill a little I gas it to the floor and it takes about 30 seconds to kick in..Your help on this would be great.

This is my 99 jimmy with 199,000 and well kept.But some idling issues..