wierd noise .........

i have a 99 alero (2.4) and whenever i start it a noise like a "clunk" is heard immedietly after i start it from the bottom of my car. It only happens when i start it. any suggestions of what it might be?


Another noise is also made whenever i shift from reverse to drive; or drive to reverse. The noise seems to be coming from the transmition (i could be wrong, ive just flushed the tranny oil & changed the spark plugs) Any ideas on what that could be?

i had something like this too, it was my intake air temp sensor which is located just after your air filter (3.4L v6) it was a $10 piece i believe, but the wires also need to be replaced per a service bulletin, the wires were around $15 from the dealer