had motor replaced in a 97 grand am SE

motor threw a rod a week after i bought it.seller helped in locating another motor from a wreck.mechanic didn't hook up all grounds or cooling fan.would not pass inspection.all sorts of codes came up.a different mechanic finished hooking everything up,cleared the computer and told me to drive it at least 50 miles before reinspection.It failed again.It runs ok with exception of a slight stall(hesitation) at take off.i have spent as much s i paid for it on repairs.so i need to do what i can myself to save some money.check engine light stays on constantly.ETS light stays on.hesitation at take off. a hissing noise from what seems to be around alternator.also configuration of motor does not match my haynes manual.everything seems backward making it difficult to locate parts.i was told i need new IAC valve,oxygen sensor,EGR valve, etc.which should i do first? Also what could cause a rod to go like that and do i need to do something to prevent this from happening again.motor never showed signs of getting hot.and it had oil.i have added fuel injector cleaner earlier today.any advice to get me started?Auto Zone will be this morning.thank you......oh yeah 2.4Liter twin cam engine.automatic.

If all of the items you mentioned are bad then you will need to replace them all. The hissing sound may be a broken or loose vacuum line. All of the items you mentioned are very easy to change and should only take a few minutes. The EGR is located on the front of the engine but I suggest that you clean the lines to the EGR as well. The IAC is on the throttle body and comes off with a couple of bolts. The O2 sensor may be the most difficult to change as you may need an O2 sensor socket. Make sure you put antiseize on the threads of the O2 sensor so you can get it off again.

As for the other engine anything could have gone wrong. The rod could have been weak or the bearing could have seized up causing the rod to break. You could have dropped a valve that caused it or the oil pump could have failed.

If all of the items you mentioned are bad then you will need to replace them all. The hissing sound may be a broken or loose vacuum line. All of the items you mentioned are very easy to change and should only take a few minutes. The EGR is located on the front of the engine but I suggest that you clean the lines to the EGR as well. The IAC is on the throttle body and comes off with a couple of bolts. The O2 sensor may be the most difficult to change as you may need an O2 sensor socket. Make sure you put antiseize on the threads of the O2 sensor so you can get it off again.

As for the other engine anything could have gone wrong. The rod could have been weak or the bearing could have seized up causing the rod to break. You could have dropped a valve that caused it or the oil pump could have failed.
thank you for your help.is ther any particular one i should start with.how do i tell if they're bad.

there is a sound that sounds like a pully grinding around the altanator. is there a way to grease them?

Start with the O2 sensor. Then pull the IAC and clean it with throttle body cleaner. Be careful not to move the pintel when you have it out of the throttle body. Then do the EGR valve. As far as greasing the pulley around the alternator there is no way it could be an internal bearing going bad.

When you buy the O2 Sensor check to see if it already has te anitsieze on the threads the last one I bought (Bosch I think) had the compound on the threads, The counter guy told me that most of them are comming that way.
As for the gringing noise is it from the alt. or is it comming from the tensioner pully? Sometimes when they go, it puts out a grinding noise.

When you buy the O2 Sensor check to see if it already has te anitsieze on the threads the last one I bought (Bosch I think) had the compound on the threads, The counter guy told me that most of them are comming that way.
As for the gringing noise is it from the alt. or is it comming from the tensioner pully? Sometimes when they go, it puts out a grinding noise.
sounds like alternator.hard for me to really tell.serpentine belt was replaced about 2 weeks ago.noise started soon after.quiets down after a couple miles.its worse when started cold.if engine is already warm no noise.is something about to go out?