If you haven't replaced your front O2 sensor, you might want to try that to. Pretty cheap thing to get, easy labor you can do yourself. My advice is to avoid Bosch. Just tried to hook up one of their sensors, the cable was 1/2" to short to plug into where it was supposed to. I double checked the part #, its right.
So I cut wires off the old sensor, cut the plug off the new one, and wired it to make it long enough. There are two white wires, not sure if it matters which one attaches to which plug terminal, but I tried both ways, didn't matter. Truck bogs down when I try to accelerate shortly after I start it, misses at low or high speed, and so on until its running for a while and then comes out of it. If I turn it off, same thing all over again next time I start it.
O'Reillys, my normal part store, just has Bosch and nothing else for O2 sensors. So I went to an independent local auto parts store, they had NTK (same company as NGK) sensors, which I've heard good things about. They don't have it in house, but at the warehouse. So I drive three or four miles to the opposite end of town in Saturday traffic with a misbehaving truck, get the part from the warehouse, go home. Attempt to install it later that night... they gave me the wrong sensor. They gave me one for a California emissions truck. *sigh* Plug doesn't fit.
So I will have to wait until Monday to do the exchange, and with my luck, they won't have the one I need on hand. Why have none of the 49-state sensor and lots of the Cali type in South Dakota, I don't know, but like I said, that'd be my luck.