HELP!! with my 75 Dart

Best thing to do is make sure everything is in spec. "I" would start with a compression test. Just to rule out any coincidences. I mean, if something has cause a cylinder to drop, and "just happened" at the same time as the accident, you'll be chasing your tail unless you verify all 8 have good compression. Then from there, I would check timing, points if it has them, Of course checking the compression means you have the plugs out so they would be inspected at that time. Put a vacuum gauge on it. Make sure it has a good vacuum signal. All of this is relatively easy to do, if you can operate a screwdriver. lol You just need to take each thing step by step, one at the time and you can find the problem yourself, without having to worry about some bullshitter dishonest "mechanic" getting over on you.