Could be a weak exhaust valve. A compression test will verify
if it is when you let off, the AIR diverter valve could be the issue.
If it is on accelaration, it also could be a worn camshaft lobe.
Make sure the basics are covered like the plugs, wires, cap and rotor.
Please consider a to help us answer more questions.
Sunday, April 8th, 2012 AT 2:01 PM