When I'm at a steady cruise at 40mph (lockup point) the tcc will lock for 1/2 a second, unlock for 1/2 a second and then relock. I'm fairly certain this is a tuning-related issue, what do I need to change to correct it? 2.8 v6, '165ecm w/ $32B mask.

 

Could also be the throttlecable not adjusted correctly.
Try adjust your throttlecable and see if it helps.

It should not lock, and unlock if you give steady throttle.

 

Is this a new problem since you made some tuning changes? Or did it just happen? I've had a bad VSS cause erratice operation of the TCC.

If it is from tuning, you may have to make the converter lock at a higher speed, for me I have it lock at 45-48 MPH, It would just lug and lock/unlock at slower speeds.

 

It started after I lowered the enable point from 45mph to 40mph. I reset the tv cable and I rarely notice it now.