the lights radio and everything else comes on ...i had a new starter installed 3 months ago..and the battery is good...what do you think is the problem

What does it do? Does it crank? If so, you may have a problem with the fuel system or the ignition system. If it doe not crank, you have a starter problem. Or you may have a computer problem.

did you check the alternator, the alternator is like a heart, it keeps everything running.

If indeed it cranks, sounds like it will start but does not as you let the key go back to run position, it is the small ignition box in the column. Just did this on my 1985 Lincoln Continental 2 weeks ago. Standard problem on Linc's/Fords.

This model year,the starter has a weak link at the terminal of the starter solenoid.Later model year,they use a mounting stud instead of a male connector for the solenoid.They are interchangeable