My 87 240 has some weird things going on with it. When driving uphill at pretty much any grade I have found that I can go about 70mph in fourth gear. This weekend I was going up skiing and for some reason I just had no power going up hills. Some of the steeper hill she would only do about 50 to 55 mph. I have never experienced this little power before. There was no wind or other factor that would slow me down. I don't know if it is related at all but I don't get as good of gas milage in the winter time. In the summer I get about 27 mpg or so and it drops down to about 22 or so in the winter. The car also has a problem when it is starting cold that I have done alot of work on and am still in the process of figuring out but I don't think that is realted because it has has that problem for a while and not affected the power in the hills. The only real difference that I can see is that I was at a much higher elevation that I usually am driving the car. Any Ideas on what this could be I would greatly appreciate!!

The Car seems to behave normal with intown driving.

-M