Wierd noise not sure whats wrong!!!!!!

Ok the other i was driving my s12. And theres a wierd noise at acceleration at about 2000-4000rpm, it sounded like a diesel truck accelerating,and i also notice some power lose also. Please help me out?

exhaust leak? What motor is in it?

gumby, it honestly sounds like your describing the mechanical noise from the lifters. mine start to make more noise when i get near the 3k mark for the oil change, or if it becomes dirty sooner.  also possibly you might need a lifter adjustment. but without a sound clip were are just guessing.

I second the exhaust leak. Mine did that when I first got it, took awhile to isolate. CA18ET manifold was pulling one stud out of the head at rear and got an exhaust leak. I had to oversize the hole and put in helicoil and larger stud, no further problems.

Found the problem should've posted it sooner. The fan clutch just seized up....