My 2008 Ford Escape Hybrid is an AWD model with about 147,000 miles. Recently it will be on the highway and running at 3000 or more rpms on the highway at 72mph vs about 2400 that it used to run with the same tires it has now. It typically gets about 23 on the highway now or less. It runs slightly rough at low idle (when the idle comes down below about 1200). It had new plugs in the spring and does not trip any codes. The oil seems to consistently get filled about a half quart high by the shops. I don't think that would cause high rpms though. The charge/discharge gauge is in the middle when it's on the highway. It isn't a battery issue as far as I can tell it is not doing a recal.

 

Is it going into EV mode normally during around town driving?

 

I had similar symptoms to you with rough idle and lower mpg. Took it in to a Ford dealer and they had their fuel trim technician look at it. One of the MAF sensors turned out to be bad. The check engine light never came on, but the Ford tech was able to find it after a while on the computer.
There could be other issues going on with a high miler such as suspension/alignment, drivetrain, etc...might take some study to sort everything out.

 

It goes into ev mode around town once it's warmed up. It takes a really long time in the winter, but I don't think the thermostat is bad because I checked before and it will reach 190 on the highway. The MAF sensor sounds like a good place to start, that could cause a lot of performance issues.