I find that it runs great on all elevation, uphill, downhill, power on. But holding mid range seems to get it to shutter or stutter... its like it wants the pedal down or up but not steady.
Does this sound like fuel jet??

 

Blondie, by chance, does it only do it when the vehicle is around 45 mph? if so, that is the tranny unsure of what gear it wants to be in and it will make the car do some funny things. If it will do it in all gears and at various speeds, then I would first start with the spark plugs. When was the last time the plugs were changed? If it has been 50K+ miles, then atleast a check of the plugs would be called for. It is possible you have a little bit of oil in a plug well (normally the #1 cylinder, ie, the back left cylinder, is the culprit most of the time). Granted, your plugs may be due for changing too and the gap is too big now, leading to the stuttering.

By chance, are you in WA state? Sequim is one of those places that can't be in too many places. Used to live in Bremerton.

 

May well be a bad coil.