My 2003 ford ranger won't idle steady it goes from 1200 to500rpms, it has new plugs wires fuel filter, both upstream oxygen sensors, new vacuum elbow, idle air control, and air filter Hook it up to the computer and it says bank1sensor1 lean and bank2sensor1 rich and both oxygen sensors are 2days old, and I reset the computer after I put them on and the codes come back, that's the only codes it shows, any help is very much appreciated thanks in advance!

 

How does the engine run at speed?

Reads like a blocked exhaust(cat) on 1 side.
Since they are new remove/pull out one O2 sensor, try driver's side first, then start engine, yes it will be loud, lol, but see if engine smooths out, if not put that one back in and pull out the other side, same test.

If that doesn't help then you will need to do a compression test.
Another member here with 4.0l SOHC had an issue with Cam Gear slipping causing low compression on 1 bank

 

Will do, thanks for the reply. I'll try to do it tomorrow. When I'm going I can put the gas to the floor and like 3 seconds it goes same speed like I was then all the sudden it will throw me back in the seat and just take off.

 

I'm having a very similar problem. Surging idle and delayed throttle response with codes P2196 and P2198. I'm in the process of replacing/cleaning all the stuff that you listed. I'll try that exhaust trick and let you know what happened.

 

Let me know if it works for yours, I haven't had time to do it with work.. If it helps yours let me know and I'll know its my converter, but my truck only has one converter so idk if taking out both upstream sensors will make any difference for me or not? But let me know what happens with yours and good luck!

 

P2196 and 2198 indicate an issue with your forward (Upstream) oxygen sensors (stuck rich), or possibly the circuit(s) they're connected to. What do your fuel trims read as?
How's your grounding/charging system?

 

How would you check the fuel trim? Grounding/charging system? The battery and alternator seem to be working fine.

So far I have cleaned all senors/sensor connections and put in new plugs/wires. I have not checked the exhaust yet.

 

Whatever scantool you use to read the codes should have a fuel trim display. LTFT/STFT trims...unless all you have is a code reader.

Those codes indicate sensors are seeing more oxygen than they think they should, so it'll instruct the injectors to deliver more fuel...until it over delivers, and then it'll be seeing not enough oxygen, so it'll shorten the injector delivery times, adjust IAC valve based on TPS numbers...on and on until the sensors balance themselves out. if they're stuck at one end of the range they're supposed to be within, it'll never happen. Your task is to determine why they're "stuck" and reporting to the ECU what they are.

HOWEVER - it might not be those sensors reporting incorrectly.
What if you have an exhaust leak, so that outside air is getting in to be seen by the sensors, with more oxygen from fresh air than they're supposed to be seeing? that could cause more o2 around those sensors than the computer thinks it should see as well, causing all of the same things I described above...

I still bet that it's wiring. a broken/burned wire to one of the 3 sensors, a funky ground... Got a wiring diagram?

at least you know the computer works properly I believe Ford tells you to replace the o2 sensors every 60k miles. I don't think they're clean-able, like the MAF.

 

New mass air flow fixed mine.