This is my first post, but my 1988 Bronco has been having some issues lately. Whenever my radio is on it starts to drop RPMs and starts stuttering while I'm driving. When I use the power windows the tachometer goes crazy. When I use my turn signal it again starts dropping RPMs and starts stuttering and jerking. It will also randomly shut off when I am at a stoplight. I tested the battery and alternator and it read good. Would a bad ground be causing it to drop RPMs and make the engine stutter and jerk when I drive?

 

Yes, it could.

One way to be sure is to start at the battery negative terminal and remove , clean with wire brush or sandpaper every connection to sheet metal you can find.
Don't forget to do those where the battery cables connect to the engine. It is a bit of work, but usually if there is a poor ground those places get the worst corrosion , which cannot always be seen.

It would be a good idea to verify power from the ignition sw is not possibly having a problem.. If you connect a test light to the ignition supply at the ign coil so it is lit anytime the key is on, you will have a visual picture if it is dropping out. You can connect the ground clip of the test light to the power to the coil and place the test light where you can see it while driving . The pointed tip of the test light can be making contact with any metal part of the body when the key is on and the light will illuminate.
Nice simple way to see just what is happening if it is.