I was driving my 97 s10 blazer tonight and when I pressing on the gas pedal it going no problem but then it revs really high and changes gears finally. It seems to be hesisating. Sometimes I get this smell also. My service engine light was on this week and I took it to the shop and they said my cataylic converter was cracked got it fixed today. When I'm pressing the gas pedal I do get a whirring noise when it's reved really high. The shop also said it could be my spark plug wires or is it my transmission?