2004 Toyota Celica - no engine braking above 30 mph

My 2004 Toyota Celica SE with a 3.3 liter V6 and 156,000 miles developed this issue about 3 months ago. I get no engine braking at and above 30 mph. I let up on the gas and if on a sight decline or level road it is as if the cruise control is on. It is not. What is causing this? How much of my Social Security will it cost to fix?

Automatic or manual transmission?
Are the RPMs dropping?

I would check compression too.

Make up your mind . Do you have a Celica or a Camry as your other post says ?

Sounds like transmission problem and only a shop can tell you the cost if that is what it is.