Hi everyone,
I have a problem with my Focus mk1 1.6 16v 74kw. The car is having trouble starting after sitting for a long time - 10 hours. Previously, it started so that the revs jumped to 1700rpm and then slowly fell to idle. Now the car sounds like it wants to increase the revs, but immediately after the start they drop to 1000 rpm and from there they go to idle after a while. When I start the car after an hour later and engine is cold again, the start is normal as before.

The other problems I have is that when I put some load on the engine, the revs drop very low. I feel this most when the air conditioning and headlights are turned on, but the problem occours with the heating on without AC. In short, when I'm driving, everything is OK, but when I want to stop, I press the clutch and the revs drop to around 500, which causes the car to shake.
Diagnostics shows nothing. I've already tried replacing the fuel pressure regulator, the IAC valve, the throttle position sensor, I cleaned all the intake sensors and the intake itself and the PCV valve. No change. The only thing I noticed, so that both before and after the replacement, the throttle position sensor shows that it is open to 20 percent even when the pedal is not pressed, that seemed strange to me, but if this was the problem, I think it would showed even when driving without the air conditioning/heating switched on, which it does not.

Now I wondered if this could be caused by a bad battery or a dying alternator that doesn't provide enough electricity to the components. I can't measure it right now because I'm not at the car, but what do you think? Could it also cause Fuel tank vapour canister? Because when I disconnect the vaccum hose leading to it, everything is fine, but the idle speed is slightly higher.

Thank you all for every answer, I don't know what to do anymore and I apologize for my English, I'm from the Czech Republic.

 

..Have you tried to check the ecu for errors to see if it lifts any error flags on tester?