MB 300d Poor acceleration

'83 Mercedes 300D, Turbo, 165,000miles. Two issues.

1. Poor acceleration: Car accelerates very slowly. It will take about 25-35 seconds to accelerate from 0-55mph, a definite problem on the freeway. Just slow to accelerate on flats and especially uphill. Okay for now on downhill. I have to shift down to second, sometimes low, if the hill is above a slight grade and then it crawls along. The car has yet to not make it up a hill but I haven't driven on a longer stretch of hill yet.

2. Slow shift: Car will stay at about 25mph for 10-15 seconds before shifting into next gear. Doesn't seem to have problems shifting at other speeds.

I just had the car serviced where the mechanic 'tweaked' something to address the poor shifting which seemed to correlate timewise with the onset of the poor acceleration issue.

Thanks for all advice.