Here's a real puzzler...

My '86 245 is very healthy for a car with 170,000 miles on the clock. I would never dream of taking it to the track, but it accelerates and overtakes other vehicles with ease.

However, on the highway it tops out at about 80mph. It seems to hit a "dead spot" and is very reluctant to rev higher, even though I push it to 4500+ without protest in town.

The first thing that came to mind was a clogged catalytic convertor, but it will rev freely to the redline in 2nd and 3rd.

I have also noticed that recently my mileage has decreased significantly, from an average of 28mpg to 24mpg.

What do these two symptoms suggest, other than the fact that I have a lead foot?

Honestly, most of the time I obey the posted speed limit, but there are those situations where I need the power. I have never participated in a street race (what would I race anyway, motorized golf carts?). But a sudden loss of top end power and a drop in fuel economy at the same time is very strange.

Any ideas?

Thanks,

Jim