1997 Ford Fiesta 1.25 Zetec with Automatic Transmission

When it was -20°C two weeks ago, the car did not start and since i tried a little bit, the battery was almost dead.
The battery was taken of the car and charged, then mounted back on the car and the sparkplugs was changed. The car started right away.

The problem now is that car is almost not drivable on low rpm, the engine dies or goes down to 400/500 rpm when i change into D(drive) on the gearbox.
If i drive slowly and hit the brakes, the engine either dies or goes down to 400rpm and then rises again.

I've been at a garage, and the CO was rising a lot when the RPM increased the OBD reader said something about the "Lambda", "speed limit exceeded?" or something like that and
something about the engine fan. The codes was cleared.

I've tried to change to a new Lambda, cleaned all connections, i've checked the ECU internal to see if anything was burned. Testet the Idle speed
valve: when i wired it up to the battery the engine raised to approx 4000rpm. Also tried to disconnect MAF and TPS but the car was not possible to drive then. The throttle body was cleaned as well.

After changing Lambda and cleaned some parts i dont get any codes from the OBD reader, i'm now using another reader. But the problem with the engine rpm is still there.

Anyone have a clue what i could try?

 

Try disconnecting the ECU for 30 mins or so to clear previous faults, it might still be in limp home mode due to previously registered faults.

JAmes.