2 things I would check
condition of the battery, and the terminals. All the ground and power wires.
Also, the connection going into the ECM. Some of those readings make sense, but others shouldn't (like it reading forward movement..)
You may want to have the ECM reflashed with a good BIN file. Better yet, get a known good ECM and have your BIN flashed to it.
I've seen some really strange stuff going on in some Chryslers that would disappear with a reflash of the ECM.
I'd find a shop that you trust that has a Tech2 scanner, and let them do a diagnostic. The Tech2 can do things that us DIYers just can't, since it can communicate bi-directional.
Not to mention, pull and read the plugs. Being able to read plugs is a lost art, but it can really tell you what is going on, sometimes better than any computerized gadgets can.
2004 Buick LeSabre Custom FE5 GXP suspension conversion. 170Kmi
2001 Silverado 4WD 5.3L, 33" BFG ATs, Z71/Z82 pkg, 147kmi.