Dear Pierso,

Hope you're well and stay so! The first thing to check is the Idle Air Control Valve, mounted on a bracket beneath/beside the intake manifold.

Remove the valve and inspect its openings. A dust/dirt build-up can disrupt the valve's operation. Put brake cleaner on cotton-tipped swabs and carefully wipe dirt from valve openings. Have a tweezers handy to remove cotton fibers that separate from the swab's tip.

Keep the valve's end with the electrical connector pointed upwards: this keeps solvent from entering the motor compartment.

Before re-installing, use an electrical oxidation remover on the valve's contacts and on the wiring harness contacts. Deoxit has served me well.

With the valve cleaned mechanically and electrically, reinstall it. I'd guess this should improve things.

You should also inspect the large-diameter air-intake hose, that runs from the air box to the intake manifold. A crack in the corrugated section of this hose can allow unmetered air to enter. If the crack is large enough, the amount of unmetered air may exceeded the computer's corrective capacity.

Hope this helps.

Yours faithfully,

Spook