Common causes are a dirty throttle body, faulty idle air control valve, vacuum leak, or a failing crankshaft position sensor. A diagnostic scan finds the cause fast.
Here's a quick, honest answer from a working UK mechanic — what causes it, what it costs to fix, and what to do next.
Can I drive it? — Yes carefully, but stalling at junctions and roundabouts is dangerous. Get it scanned this week.
Why only at junctions? — Idle problems show up at low engine speed and warm engine — the ECU's idle map is doing the most work.
Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email bob@bobsmechanicalrepairs.co.uk.