The shop I work at is just south of you, right off of I-69.
It's called Waxwerks, and you can find our # in the phone book.
If you want a cruise control, call and tell the person answering the phone
that you drive a "George Jetson" car like Niles, and you want a cruise control!
A properly installed cruise control will typically give you better MPG due to throttle consistancy. A skilled driver staring at his insight MPG meter is a pretty good match for a cruise control as far as MPG goes, and the driver has an advantage.
A skilled driver can anticipate the terrain and actions of other drivers and use this to his/her advantage, while the cruise control can only react to real time information.
there are a number of things that can cause the problems you describe.
When your unit speeds up to the 75-80 point, and then falls back to 65-70 does it pulsate at all?
Also, is this on a manual transmission?
It's tricky to fine tune a manual transmission cruise cause acceleration is far more sensitive than an automatic, which almost acts
as a buffer between the petal and the road. there are sensitivity adjustments for the cruise control (low/med/high), and you should experiment with some different settings.
Also, make sure the installer gave you some slack between the throttle connection, and the cruise cable cause if the connection is too short, the cruise will more likely pulsate. You should confirm the pulse rate settings, and engine size settings are also acurate.
there have been a couple of times I spent more time adjusting and tweaking a cruise control than I did installing it. :?
It's just one of those things that takes alot of patience and practice.