When I accelerate hard to about 35 mph and then abruptly let off on the accelerator, there is a hard clunk in the front left wheel area. It does it every time I try. If I accelerate hard but do not let off abruptly on the accelerator, later when I slightly brake there can be a clunk or two like I ran over a branch with my left tire.
A rough running motor or lack of power can be caused by a failed distributor cap or rotor, ignition wires (or their resistors), or valve cover gasket leaks. If the valve cover gasket leaks, oil can pool where the ignition wire resistor connects to the spark plug. The resistor can fail and the spark plug may not fire because of a short circuit through the oil.