Various 190E 2.6 problems, heating up and tranny

I have a couple of problems with me 190e 2.6, 1987<br> that I just acquired. It is a beautiful car and I'd like to keep it. I am very mechanical and don't mind working on this car.<br> <br> 1. The water temp jumps all over the place. from 90c to 120c. I took the thermostat out and it makes no difference. On the Hwy it runs about 90c but AS SOOn as even begin to slow or take an exit the temp jumps right up to almost 120. Today I went around a freeway off ramp at 50mph and the temp jumped right up. Around town it heats right up. the electric fans are coming on. Three thoughts; maybe the fan is not locking up, or the radiatior needs rodding, or there is a blockage. I have had the system pressure tested and found no leak. Have you had any similar experiences. Continue for the next problem><br> 2. The tranny doesn't shift right, it goes from 1st to 3rd with a VERY BRIEF stop in second. Is this supposed to be a 3 or 4 speed auto. How hard are these to service? I also have a 300cd, is this basically the same tranny? <br>