Slow acceleration. 2000 VW Beetle. Was running

There are probably two coolant temp sensors--one for the dash display and one for the ECU to do fuel trim. Unlikely that both have failed at same time, but possible. First, insure coolant thermostat is not stuck open preventing normal warm up, then test or replace coolant temp sensor for the ECU.

could be the shifter cable is bad. would need to be inspected to see if things are working right

Fuel filter?

check fuel pump.if there is a small , even hairline crack in the diaphram it will do as yours does. good luck.

try installing a new brake light switch ref. haynes repair manual for vw 98 - 2002.

maybe coil pac!!!

I had that problem for the longest time. I had to clean the Mass Air Flow Sensor. Very easy to get to. Go to any auto parts store and ask them for the MAFS Spray. If cleaning it doesn't work, you may need to replace the MAFS. Once again easy to replace. Make sure you put it back nice and tight.....

the heater core could be leaking that explains the fog but i would have the water pump checked

well is the battery draining over the time its sitting?
could be a bad battery or alternator, and/or you might have something on the car constantly draining power from the battery.
best to have it looked at by a mechanic.

check the plastic connectors in the cooling system.vw is notorious for the plastic stuff cracking causing a slow leak