'87 Accord Lx Automatic - carburetted

At 70mph cars is turning about 2750rpm. The vehicles rpm's will sporadically kick up to 3000 rpm, hold for awhile, then kick back down to 2750 rpm. This pattern happens at highway speeds between about 60-75mph. It's as though it's downshifting. Seems to happen more when going down a grade or hill, although it has also done so on flat stretches of road. Will occur with or without the use of cruise control.

I suspect a vacuum valve or throttle cable adjustment.

The car idles high(2000rpm) when first started in the morning. Takes longer than it should to kick down to normal idle speed. Don't know if there's a relationship between these two problems.

Thanks for your time.

It could be the choke/fast idle linkage or the torque converter locking up and unlocking too often. Those would be the first things I would check.