Engine smokes on tickover

ASTRA 1.6 16V CD SALOON. TOP OF RANGE.1999 45000 MILES.

I HAVE JUST SPENT A FORTUNE ON THIS CAR. NEW VALVE SEALS, HEAD SET, HEAD SKIM, HEADBOLTS, TIMING BELT, WATERPUMP, EXHAUST, SERVICE , ETC.( ALL AT MATES RATES BUT STILL ADDING UPTO OVER £500).ENGINE BORES SHOWED NO WEAR. THE PROBLEM WAS THE ENGINE SMOKING AFTER BEING RUN ON TICK OVER FOR A WHILE. IT WOULD THEN CLEAR UNDER NORMAL DRIVING AND START AGAIN AFTER TICKING OVER. OBVIOUSLY THIS CAUSED A PROBLEM FOR THE MOT HENCE THE WORK BEING DONE ALONG WITH SOME OTHER MINOR JOBS TO GET A PASS LAST WEEK. ALL HAS BEEN WELL SINCE, UNTILL TODAY AND IT'S STARTED SMOKING AGAIN. I HAVE NOW LOST THE WILL WITH THIS CAR BUT NEED TO RECOUP SOME OF MY OUTLAY. IT COULD BE A QUICK FIX- I DON'T KNOW - SOMEONE HAS SUGGESTED A BREATHER PIPE PROBLEM, IT RUNS FINE AND HAS PLENTY OF POWER, BUT I'M NOT PREPARED TO SPEND ANYMORE MONEY ON IT FINDING OUT.