sidenotes:
1)doesn't your CARB compliant Ram have additional O2 sensors not found on FED compliant vehicles? I have two 1999s, Ram and GM. I know one only has 1 bank from long ago, don't know about the other as I haven't had any issues in a long time. Not sure which is which.
2)"shop can't diagnose" does that mean in their allotted 0.5hrs? Or time paid to diagnose by the hour?
anyway
Are you saying at a steady cruise rpm of 3k, upstream flatlines rich at 0.7V? Ignoring accelerating which will put you in open loop.

Is data good on other closed loop sensors? MAP , ECT, IAT, TPS, CKP. add CMP when considering ignition timing. As stumped as you are now, I would go as far as component testing like reading MAP data on scantool with engine off (should read atmospheric from weather channel ~29.9in/Hg), then pull it and apply vacuum with a hand vacuum gauge and read data. Ignition on, checking TPS data as you slowly work the accelerator back and forth. All I'm seeing is y'all fixating on that o2. cat is new, o2 voltage is responding correctly to rich/lean.

It's not running too lean, since you have a steady downstream signal, so you're still getting lean/rich fluctuations. If it was too lean, you'd saturate the catalyst with oxygen, and downstream signal would mimic upstream waveform and give a 420



After checking continuity on O2 connector sensor ground and sensor signal back to the PCM, still no problem found? The point where you said o2 was sometimes staying at .008v? wasnt sure if you said that is a current issue.
This is when you go find Shop #3 that has an oscilloscope and knows how to use it and scopes your primary and secondary ignition and O2 waveforms.

 

It runs smooth no stalls misses or anything like that and no codes anymore. Still can do 75 up a mountain highway. The main concern was the acceleration loss which the new cat greatly improved but i almost feel like it still is slightly more sluggish off the line then it was before all the work. Whats wierd is this is my third second gen my other 2 being 01's one with 5.9 and 1 with 5.2 and when i bought this truck i kepts thinking it felt like it had alittle more umph off the line and would chirp fairly easy compared to the other 2 especially being its a long bed with a massive plenum plate leak but now it feels pretty much the same as the others which are gutless until they hit 2k or so. Honestly if i didnt have the scanner i may have called it good by now but im in a smog state so i worry about it passing if it is not right.

I have a hemifever stc in the mail but alittle hesitant to slap it on if its not right lol.

 

This truck only has 1 bank so 1 cat 2 o2 sensors. The .006 is current at idle both sensors. I have done alot of other diagnostics as you said and everything seems to consistently check out. The last shop was supposed to have it for a hour. He is a 2nd gen fan and kept it for 2 days then felt bad he couldn't pin it down and charged a hour.
i will try applying vac like you said and see if i get any different results. Thanks

 

What size tires are you running and what is your gear ratio in the rear axle? Lastly, is your truck 4WD?

 

im running 285 75 16 It is 4x4 its actually my plow truck . I assumed 3.55 but would have to confirm

 

I got an old HemiFever SCT from around 2010 or so. It will store your stock tune, then you can install Sean's custom tunes. Then you can revert to stock tune for smogging. Pretty easy only takes a couple minutes to swap back and forth.

Maybe your peppier Ram wasn't death flashed?

.006 Current or voltage? You meant voltage, right? I heard aftermarket Ram O2 sensors will get temporarily get stuck high or low voltage before acting normally. Only for dodge, never heard this issue for GM.

I'd make sure you don't have an intermittent connection in your O2 harness that gets worse from engine vibration while its running.. wiggle test the harness while continuity testing both signal ground and signal output - including the connector terminals themselves ... so u can diagnose between harness issue or the O2 just being glitchy like i described

So that 2nd gen guy, maybe he doesn't have an oscilloscope to analyze your sec/prim ignition and O2 waveforms. Might be next to do for the lean.

 

I experienced sluggish takeoffs with my truck after I installed 285 75-16 (33" tall) tires with 3.54 gearing. I ended up upgrading to 4.10 gearing in my front and rear axles and it made a world of difference in takeoffs and overall acceleration. The 4.10 gearing upgrade made the truck fun to drive again.

 

i did just recently change them too and went to a mud terrain from a 265 at . Definitely something to consider

 

.006 is voltage .

I have wondered the same i will l try it and see. I have been leaning twords a wire issue but all i have tried is ohming and visual which i haven't found anything yet .