As for the surge and strain when going up a hill, I think I have a clue (because my 300D sometimes does it). Several years ago I adjusted the vacuum control valve on my car and greatly improved this problem. Although I don't recall the particulars of how this worked (had a little better concept when I worked on it than I do now), it is my opinion that the vacuum reaches a point when accelerating up a hill that it cannot quite decide whether to be in 3rd gear or 4th. Sort of halfheartedly tries to shift, resulting in a 3-4 flare. In the rare event that this happens, I floor the accelerator and egage the kickdown switch. Transmission shifts down to third and all is well. Prior to adjusting the vacuum control valve, I couldn't even engage the kickdown switch. As stated above, my adjustments helped a lot, but are not 100%. Rather than continue adjusting and adjusting, I learned to live with it. Later bought a 300 SD and got it right the first time I adjusted it. I may be off base on this one, but if so maybe some brighter member can chime in.

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John Schroader
bio burnin' 83 300D, '83 300 SD, '79 240D
"I've never met a man who was good at making excuses who was good at anything else" Ben Franklin
"You cannot permanently help a man by doing for him what he could and should do for himself" Abraham Lincoln