Monte and Andy
For perfect 4ths and 5ths to lock in, you should sing the songs that have those intervals.
For perfect 4th, use "Here comes the bride"
For perfect 5th use "Star wars theme" or "Top gun theme". I think even "Flinstones theme" starts with descending perfect 5th. Money for nothing by Dire straits starts with perfect 4th hammering on the perfect 5th. Smoke on the water main riff is using just perfect 4ths...
Idea is to pick one tune for each and as soon as you hear starting note, sing the next note from it. Use the song, lock it in your ear and then check your answers.
More advanced approach is by using triad inversions, but that only works for perfect 4th!
2nd inversion of major and minor triads use perfect 4th interval between 5th and root followed by some sort of 3rd.
Hope that helps!
Pedja