95 Mustang 50 with manual trans engine speeds up fast and slows down a couple times in row and check engine light flashes?

Answer 1

if havent checked already look at the throttle body behind the butterfly valve and see if you have a carbon build up which in turn screws with throttle position sensor giving it a mis-reading

Answer 2

The symptoms you described could indicate misfiring in the engine cylinders. This could be caused by issues such as faulty spark plugs, a failing ignition coil, or a vacuum leak. It is recommended to have the vehicle diagnosed by a mechanic to determine the exact cause of the problem and address it accordingly. Driving with a flashing check engine light can potentially cause damage to the catalytic converter.