got a pantera with twin 496/375 driver side motor has a pop at idle been to dealer and still cant figure out problem.all tests came up good runs fine but still pops at low rpm what else can you try everything from compression test to leakdown to injectors to coils you name it it was checked where do i go next???

Baddogg,
Is the engine popping or missing at idle? If it is missing it could be a broken valve spring.

Check if the exhaust is leaking water into the engine

Baddogg:
You say the 496 is popping at idle. Is the popping comming from the exhaust, if so which side of the motor, or is it comming out the throttle body into the wire mesh of the arrestor. Popping out the exhaust at idle generally comes from an exhaust valve stuck open or broken valve spring on the valve or a badly burned exhaust valve. Two of these possibles would have shown as low compression on the compression test, a weak or broken valve spring could mask the problem on a compression test, but the popping would get worse under load or at a higher idle. Popping out the intake side means much the same problems with an intake valve. Has the dealer or mechanic hooked up a scan tool and does it show anything? Another possible problem could be in the crank position sender. Simple easy check is two swap them between motors and see if the problem moves to the other motor. Just some starting points, but we need more indication about where the popping is comming from and what it does at slightly higher rpms. If you've got a bad valve or spring, don't rev the heck out of the motor, you'll definitly make a lot of damage.
Raylar