Revs not going to idle instantly after releasing throttle

[mihkel]

After cleaning throttle body revs are not dropping to idle (800) instantly, it sits few seconds on 1.7k and then slowly goes to idle. I've tried to look for vacuum leaks with brake cleaner but no luck. What can be the cause?
Today when I took it to 50 mile ride, fuel consumption was normal but at some point it just lost all the power on low revs - it just stayed right above 600 rpm. Did not stop though.

Any ideas what can cause that?

Car Audi A3, 1.6l year 1997.

 

[JOSE8LT]

Might need a throttle alignment bud. Can be done with VCDS check youtube

 

[badger5]

on 1.8t, its often a dodgy clutch pedal switch

 

[mihkel]

Unfortunaltely i do not have registered VCDS reader, only shareware. Today I checked for the faul codes:

00537 - Lambda (Oxygen Sensor) Regulation: Lower Limit
Possible Symptoms

• Lambda Control inactive
• Engine running rough

Possible Causes

• Activated Charcoal Filter Solenoid Valve 1 (N80) leaking/sticking
• Injector faulty (not closing completely)
• Fuel Pressure Regulator faulty

Possible Solutions

• Check/Replace Activated Charcoal Filter Solenoid Valve 1 (N80)
• Check/Replace/Clean Injector(s)
• Check Fuel Pressure Regulator

The code did come back after cleaning and rerunning the engine. The engine does not run rough in any ways. I have noticed some power loss.