Don't know if this issue is related to what I've experienced or not. The thread did capture my attention though.
Back around 2001, I modded a '98 Mustang GT at 22k miles with the 4R70W. Gears, driveshaft, shift kit, girdle cover, TC, CAI, underdrive pulley, custom tune. A day or two after completion, I experienced a shudder, stumble and stall at low speed. Restarted the car and it ran fine. Tuner stated to keep him informed. Car ran flawlessly until I crashed it at 101k miles in 2011 - complete tuneup at 96k miles a year or two earlier.
Fast forward to 2018. My '04 bone stock Marauder with 41k miles just came out of MartyO's shop with nearly identical mods. Not long after leaving the hotel in Hiram, GA this past sunday the Marauder experienced nearly identical symptoms although it didn't stall - car regained its composure and I completed the remainder of my 230 mile trip flawlessly.
My thinking in both incidents is the ECM is/was adjusting to its new operating parameters?
Current Garage:
2005 Mustang GT Premium
2019 Ranger Lariat Super Crewcab 4WD
2015 Triumph Trophy SE
“You've gotta dance like there's nobody watching,
Love like you'll never be hurt,
Sing like there's nobody listening,
And live like it's heaven on earth.”
― William W. Purkey