I'm just looking for suggestions on this one. I've got a '92 2.3l 5spd, mechanically sound AFAIK. It's always been a bit sluggish, it pulls it's self fine, but with the A/C on it really struggles to maintain speed, especially with any wind. I run KOEO and KOER tests, and got 111, system pass, followed by 173, and 181. 173 is "Lack of oxygen sensor (HEGO) [HO2S-2*] Switches, indicates lean", 181 is "Fuel system at rich adaptive limit at part throttle, system lean". On the KOER test I got a 538- "Insufficient RPM change during ER dynamic response test or operator error". The truck stumbles like it's lean, it never fully misses, it just doesn't run smooth and strong, it surges slightly, and lacks power. At WOT it comes out of it, making me think sensor. I just installed a new O2 sensor, probably 1-2 months ago, it ran the same before and after. It needs plugs, I pulled both #1's and both electrodes are erroded, but not unservicable. The plug wires will get replaced, the one I tested showed ~7500 Ohms resistence. But I have trouble believing that plugs and wires would cause it to show lean. I've been brainstorming, I'd appreciate any help anyone can give. I've wondered about a failing TPS, since code 181 is a continuous memory code. I don't really understand the 173 code, so if anyone could clarify the definition a little, it would help. The 538 doesn't surprise me that much, and I'm guessing it may go away with the problem fixed. OTOH it also points toward the TPS IMO. I'll put a DVOM on the TPS and check for spikes or dead spots, but I'd welcome any other suggestions, or opinions on whether I'm barking up the right tree. I'm driving it, shoot I'm getting 25-27 MPG, so it's not effecting the mixture too much, but if it isn't right, it should be fixed. Thanks in advance.
Smitty...

 

I'd start out by looking for vacuum leaks, i.e., cracked vacuum lines or bad connections (including those associated with PCV and EGR systems). Clean the MAF sensor, too.

How old is the fuel filter? The old plugs and wires can't be helping the situation.

 

Thanks Rock, I hadn't thought of vacuum leaks. There are a few things I forgot to put in the first post. The fuel filter was replaced at the same time as the O2 sensor, I also cleaned the MAF at that time. I'm going to mess with it today, along with checking the TPS, I'll run an unlit torch over the vacuum system. I'll also clean the EGR valve and port, and I suppose I should replace the PCV valve as a matter of principal.