Working on a few small problems with my SE.

1. Have a surging on deceleration (like an abrupt on/off throttling). I am thinking I need a new deceleration microswitch. Is this part plug n play?

2. Oil Pressure takes a few seconds to rise on cold start. Maybe 4 seconds. I can hear lifter clatter while before pressure rises. Once oil pressure pegs, idle drops to 750 now, from 1000. Any thoughts? Thinner oil? Time for synthetic? New Lifter(s)?

3. This problem may be more complicated. Car stumbles when the temp gauge is between 55C and 80C in the morning. When restarting after engine is hot (80C), I have major hesitation for a few minutes. Goes away and afterwards everything is fine- pulls smoothly to 6500 in all gears

DC is ~50%. 49% in open loop.

Any advise? I have a hankerin' for some tinkerin'.

__________________
'90 300SE 298k
-300K and it gets put into retirement.
'80 300D 255k Purchased new by family in 1980.

Had a:
1973 220 (gas)
1980 300SD
1992 400E