Hi,
There could be a few things causing this. First, make sure there are no engine vacuum leaks. Here is a link that explains how that is done:
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
Next, the engine idle speed is controlled by what is called an idle air control valve. Here are the directions for testing that. The attached pic correlates with these directions.
2001 Toyota Truck Tundra Access Cab LTD 2WD V8-4.7L (2UZ-FE)
Air Control Valve
Vehicle Powertrain Management Fuel Delivery and Air Induction Idle Up Control Valve Testing and Inspection Component Tests and General Diagnostics Air Control Valve
AIR CONTROL VALVE
INSPECTION
1. TURN AIR CONDITIONING SWITCH OFF
pic 1
2. CHECK IDLE-UP
a. Start the engine and run it at idle.
b. Fully turn the steering wheel.
c. Check that the engine rotations decrease when the vacuum hose of the air control valve is pinched.
d. Check that the engine rotations increase when the hose is released.
________________________________
Start with these checks and let me know the results. Also, let me know if the check engine light is staying on when the engine is running.
Take care,
Joe
Image (Click to make bigger)
Tuesday, June 30th, 2020 AT 10:34 PM