I think the 1st graph is what I'm looking for , but it's all smooshed together so I can't make any sense of it. Try turning your device horizontally and zooming in a bit so you can actually see each line.

 

What other things can you display? Knock retard? Misfire count? EGR? I'm curious if you are getting a misfire causing the stumble or something else like a stuck EGR.

 

Probably a longshot, about six years ago my ‘89 G20, 5.0 (170k) developed a situation where it would stall at stoplights and stop signs. I had to put it in neutral and give it the gas for higher RPMs to keep it from stalling. Reversing was an incredible drag, I had to keep my left foot on the brake, while keeping the RPMs high enough to keep it from stalling. I looked pretty hard, I put a in new rotor and distributor cap at some point.. I finally took it to a sharp mechanic I know, he discovered it was the distributor itself that was bad. Major friction inside. Probably a longshot that it is your problem, but that’s something I never would’ve thought to look at myself.

It idled so sweetly after he put in a new one.

 

Sorry it took me so long. That scanner app is confusing and I don't really understand a bit of it.
Here are the two charts. Red is Bank 1 sensor 1, the other is Bank 2 sensor 1

 

Here are the same two sensors a few hours later. One shot is in Park the other in reverse or drive while it is shuddering.

Sitting still in park

Sitting still in reverse.

 

 

Okay so I finally got all the O2 sensors replaced with AC Delco oem sensors.
There has been no change to the symptoms or the problem. I'm lost at this point. Exhausted all options that I know at this time. If anyone has an idea, I'm willing to listen. Still no codes on the reader. Frustrated!

 

Well guys, it's been a long couple of months.
O2 sensors were replaced, engine temperature sensor replaced and the idle air control. MAF cleaned.
With all that being said, let's go back to the beginning. I had took this van to Pep Boys to replace the intake manifold gasket. They offered a complete tune up also. Now keep in mind this problem didn't start until after that repair. The van never threw a code except for the bank 1 sensor 1 O2 that I replaced.
Last week I finally got a code P0301. Cylinder 1 misfire detected. Plugs had been changed during tune up. So I decided to check to see if the number 1 plug was bad. So after removing the left front tire and rain sheild the Plugs were easy to get to.
Well low and behold, the plug wire was not pushed onto the end of the number 1 plug. It was just sitting there like it was in but wasn't. Wow, just wow! I pushed it on and drove the van and problem solved.
I want to thank all who tried to help with this situation.
Special thanks to mountainmanjoe, for his time spent try to help me with this problem.

 

Glad you found the problem 👍
I'm surprised the misfire code didn't come up sooner.

 

Read this whole thread with interest. Mountainmanjoe is excellent!!! I`m amazed at how I`m so eager to throw parts at a problem without checking all the obvious stuff first- like trusting a mechanic to plug stuff back in, and install plug wires... Many happy miles, guys!