Well here lately I have randomly been having a real lean condition that will make the truck fall on its face for a really short time and then pick right back up. It does it at cruising speed and does fine at wot. I logged a little today and it showed the ect going from 203 to 46 could the ECT sensor be going out and causing this? Here is a screen shot.

 

bizzare....bump for ya!

 

is there any codes in the PCM?
seems like its goin to be the ECT sensor, or a bad connection.

if you look at your tune, when your ECT is that low its goin to be rich. i see your Commanded AFR is 11.7 at 32% throttle.
Thats your problem..
Try to disconnect the ECT sensor and check for any corrosion or anything.

 

Glad you cought that I will check the sensor and/or change it this afternoon and see if it changes anything.

 

You went lean but your IDC went Up?
ECT sensor could be bad, wouldn't hurt to change it. Cant cost much.

 

The wideband pegs rich first then swings back lean. I am going to change it and see if it helps or stops it.