My 90 Vanagon, cranks up and runs great, until its warm. When slowing down in gear and then disengaging clutch, idle drops to 1-200 RPM's, bounces there, until it stalls. Starter will turn over motor but will not restart, unless it sits for 30-60 min. However, if it does this on a hill, I can let it roll down the hill to about 5mph in neutral and pop the clutch. Fires back up and good to go. If RPMS at highway speeds I can drive all day.

Work done so far:
Collent Temp Sensors replaced
New Spark Plugs
Wires, cap, rotors
Battery
Fuel Pressure Regulator
Cleaned grounds
Cleaned Mass Airflow sensor
New fuel filter

What should be next?

Thank you!