My 87 bonny when using steady throttle on the highway, seems to drop out of gear, or its the TC unlocking. It does it in 3rd and OD under no load, even feel it when im slowing down (no brakes, just taking my foot off the gas). i notice a 3-500 rpm jump, and you can physically feel the TC unlocking, then about 5 seconds later, it locks back up and the RPMs go back down. It unlocks at least once every 30 seconds in either gear. Any ideas?

How are your engine temps? Thermostat changed recently?

When you take your foot off the gas (TPS under 2.5%) or touch the brake (is the brake switch adjusted properly ?), the TCC is supposed to unlock. DFCO will then jump the RPM.

Other than that, if the coolant temp drops under 146F (can check with a scan tool) the TCC will unlock also.

my concern is the repeated (every 15 seconds or so) on steady throttle, the unlocking feeling, and the rpm jump. unless the temp is going under 146 every 15 seconds, the TC should stay locked.

I wouldn't lose too much sleep over this. The operation of your TCC sounds normal too me. Mine does the same thing when I'm doing a "Steady" 65mph. I constantly hear it going in and out of OD(unlocking/locking the TCC). You may not realize that you are taking you foot off the gas ever so slightly and still remaining at speed. Not to worry. Enjoy the ride.

i just find it odd that ive driven this for 20k miles and all of a sudden its doing it, and its doing it when im not in OD