Car bogs down like its out of gas

This is so simple and obvious, but I'll bet I'm not the last one that had this happen to them. Back in the day with my 71 340 Duster, I had the same problem. Looked everywhere, but no matter what I did, still had the same issue. While in the carport cursing, my wife asked what was going on, and why I was so mad. I told what the issue was and she calmly asked "did you check the air filter?". I thought, come-on that can't be the problem, what does she know anyway, but to keep peace and quiet in the family, I did.
New air filter solved the issue