VW Cabriolet RPM decreases

Hi, it sounds like you have dirt, water ,gunk & grime in your inline factory fuel filter ,.Its located between the tank & the inlet manifold,.
once you located, have it changed it, or have it changed, (its a steel canister with flow arrow) ,check for lacquer peel, which is a sealant they sometimes use in fuel tanks, check contents of old canister by pouring remainder into a container and check for this, it will be flacky particals, if severe, have tank tanken out of car & cleaned, this is due to not having the tank full most the time, Also, check your air cleaner , it will help with the cars performance. hope this helps, Kipper make sure arrow on filter face front of car....

I would replace the oil pressure sending unit first and see if that corrects this.

The Oil light is a dreaded sight, especially at idle. Usually if an oil pump fails, it dies, the same with an oil pressure sender. I had the same problem with a 97 neon, at idle the oil light comes on... (192,000 miles). If the oil used at the oil change was a thinner viscosity than what was in there, that could cause it. If not, it could be bearings going bad on the motor creating a low pressure situation. I fixed it by going to a thicker viscosity, from 5w-30 to 10w-30, and in a week the light went off... this was 7 months ago. Just food for thought, hope this helps.

from my knowledge that is right, old cabrios have only a three gear transmission so the engine will be running higher rpms

it could be your thermostat has ceased to open has caused the problem,you may need to replace it, or your water pump has is faulty & needs to be replaced....hope this helps....cheers.

Check the fuel pump, it may not be functioning.

It could be your starter. I had that problem with my vw cabriolet and finaly found out that the heat from the engine causes the starter solenoid to stop working and not engaging the starter.

The vibration at that high rpm is most likely coming from the torque convertor and if a manual transmission , then clutch issues.

change thermostat if that dont work change heater core if that dont work change your intake manifold gasket

Need a fuel distribution box for a 1988 vw cabriolet "Karman" Gas motor.