Maybe a bad O2 sensor?

[Jimmybeam]

Been having a problem lately. I'll start it up and it will run great for about 2 mins, then it wants to sputter and hop when I pull out and run really rough until about 2500rpm. Sometimes it will stall out when I come to a stop. It's an 89 with a 350 and TBI. Every now and then the check engine light will come on and I pulled codes for a TPS and a 44 for a lean condition. I replaced the TPS, same issue and still getting a code 44 here and there. The motor is pretty new so are all the sensors, but I was having a problem with it running too rich when I first got it going so I'm wondering if maybe that screwed up the O2 sensor in the long run. Just trying to get an idea of what else it could be before I try changing that out. The exhaust is the only thing I didn't put together myself and they put the O2 sensor at a real pain in the ass spot to get at. Any ideas?

[Melonhead]

I had similar problems with my 94 Blazer. The stock 4.3 and out of the blue it would run rough and higher idle. I tripped a couple codes which I can't remember right now. I too had replaced my TPS. I looked at my Haynes manual and found the wires to the TPS. I figured Ihad nothing to lose. I inserted a needle into the 5 volt wire reference, return, and the ground. I turned on the key to run and checked my points with a volt meter. My reference was good from the computer, but the feedback was high. I twisted the throttle to see if any change. The feedback was as 5 volts by 1/4 throttle. Well, lets see if it is the sensor, so I removed it and did the same test. It acted correctly. When I reinstalled the sensor, I noticed I had installed it wrong before. Once back on the TB, I tested again. It worked correctly. I started the engine and the problem was gone. What a headache for a small screw up. I never noticed the problem until I tryed to raise my idle a little.

[RONSTPIS10]

i would check the o2 sensor the computer is set to run at a preset fuel setting until engine gets up to temp then it uses o2 to adjust fuel ratio

[chris1972]

just a reminder some time the computer will trick you out while saying it too lean but could be too rich...the computer trying to lean it out ..that may set a code 44...for being lean

[4more]

I might be thinking wrong here but try the EGR vavle. just unhook and plug the vacuum line.the valve may be opening to soon. good luck