Do you have an automatic trans? Electronically controlled? Reason I ask is because pre-411 swap I ran a VE tuned blackbox. I don't recall if I ran the 411 MAFless but I don't see why I would have. I do recall that being MAFless caused the trans line pressures to max out. I'm not sure if a COS would fix this or not. With the Transgo in the 4L60 I ended up cracking the case where the servo sits. It wasn't until well after the 4L80 swap that I plugged it back in. I think I plugged it back in right after the 411 swap because it was shifting so harshly no matter what settings I changed. I went so far as to double the factory torque reduction on upshifts and it did nothing. So I plugged it in and forgot about it. The next day on my way home from work the truck was shifting much more smoothly so I went into the tune and altered shift times to my liking and the truck took to it. I'm glad I plugged it back in, sure would have sucked to frag another trans.