ticking noise

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I RECENTLY STARTED HEARING TICKING TO A HEAVY THUMPING NOISES WHEN GIVING MY GMC SAFARI VAN GAS AND A RAPID TAPPING SOUND FOR A FEW SECONDS AFTER I LET OFF THE GAS. I HAD A NEW FLYHEEL PUT IN THE SAME WEEK IT STARTED THIS. BUT I'VE NOTICED LATELY THERE IS NO TICKING WHEN I START THE VAN AND LET IT IDLE AND IF I DRIVE MORE THAN 10 TO 20 MILES WHEN I SHUT IT OFF IT SMELLS OF BURNT RUBBER COMING FROM UNDER THE VAN. SO I HOPE THERE ISN'T A ROD OR BEARING PLOBLEM. DOES ANYONE GOT ANY IDEAS WHAT MIGHT HAVE WENT WRONG HERE? ANY IDEAS ARE BETTER THEN A BLANK. SO PLEASE HELP. AND HAVE A GOOD XMAS TO ALL. THANKS