ok, yesterday i went wheelin...got on it pretty good. driving home on the road, and the throttle response is not there...the motor revs just like it would...but does not respond. I hear knocking near the oil pan...so obviously something is wrong. What would the knocking be from...a rod? Also, if the top end is fine...can you just rebuild the bottom end, or should you just go ahead and rebuild all of it? Ill drop the oil pan later, but what should i expect and what should i look for...what are things in the bottom end of the motor that can be replaced without having to rebuild the whole bottom end?

First off, what year, make, amd model is your vehicle. Secondly, what did your oil pressure look like? Finally, is this a manual or automatic? Just trying to get some basic info before a diagnosis can be made.

If it is coming from the lower end it is most likely a spun rod or crank bearing. either one will hurt your motors throttle response/performance. If you drain the oil and pull the pan there would be shaving in the oil and more settled at the bottom of the pan. On most motors you can redo the lower end with out doing the upper, but if you have the time and the money you should rebuild or at least tear it apart and clean it because the filter does not trap every single shaving and they are probably all over the rest of the motor. It would probably be cost effective to do the whole thing.