as for the weak performance after a time parked, it points to air leaks, in the fuel lines. the easiest way to find leaks is to bend the lines, and they'll weep fuel, or show cracks. also, if you pressurize the fuel tank, to about 1 or 2 psi, (I use a shop vac) the lines that are leaking will show fuel most often.

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John HAUL AWAY, OR CRUSHED CARS!!! HELP ME keep the cars out of the crusher! A/C Thread
"as I ride with my a/c on... I have fond memories of sweaty oily saturdays and spewing R12 into the air. THANKS for all you do!

My drivers:
1987 190D 2.5Turbo
1987 560SL convertible
1987 190D 2.5-5SPEED!!!

1987 300TD
2005 Dodge Sprinter 2500 158"WB
1994GMC 2500 6.5Turbo truck... I had to put the ladder somewhere!