Engine Cutting Out

Just had head gasket replaced and a new fault has developed. When using power steering at tickover speed the revs drop and engine dies. Car drives fine with a/c, lights etc on but even when parked if pulling wheel from side to side the revs surge between 500 and 1000 if I keep wheel on full lock engine becomes erratic. Any ideas?

I would try the following. Prepare to pull away in first gear. Get the clutch to bite point and let the car start rolling WITHOUT touching the throttle. If you can get rolling and keep rolling without touching the trottle and the engine RPM maintains at idle then I would say the problem is with the power steering. Otherwise, if the engine can't pull at idle then there is something wrong engine wise. Given the work done so far I would suggest a compression test on all pots.

Do you have air con? What happens is you switch that on with the engine at idle?

Car drives fine with air con on and all electrics. Problem is more noticable at night when parking etc as that is when engine cuts out. When sitting with enginge ticking over and moving steering from right to left, rev counter surges from about 500 to 1000 revs. With car stopped and A/C on lights on etc tickover is steady 1000 to 1050 revs. Reverse parking is really bad probably cos you are using lower revs anyway. Sorry for delay in answering, but working from internet cafe in Spain.
Thanks Rock

Sounds like the belt tensioner?

Check all the PAS, AC, alternator belts