ignition timing (knocking sound on pressing the gas pedal)

Engine redone recently by a garage mechanic, starting is bit sluggish on cranking and then the engine starts on idle.After the temp reaches normal and AC is turned on, engine idling speed starts to vary, at times tends to stop. At this time when I turn the steering wheel , the engine cuts out. I got it checked by a computer guy and he said the timer on the camshaft is stuck on the advanced side. Its been several days I am stuck with this problem and unfortunately the local parts supplier has run out of stock for this part.( I don't know the correct part name )
Please help me out .