My 87 300D recently had an injector pump replaced. I had just driven it around town til a recent trip and at 65-70 mph it began to feel as though it was a gas engine misfiring(skipping)--when I turned the AC off it returned to smooth operation---that I think says to me the problem is in the AC--so I have observed the compressor clutch for a lengthy time and it is quiet and I see nothing in it's cycling process that would put such a drag on the engine as to make it feel like a misfire. The AC blows cold-----I am at a loss as to where to go from here --any ideas?
thanks
joel