Am I just rusty or is this a problem?

So I've had my 1973 duster for about a year now and when gas prices went crazy last year I parked in the garage and didn't drive it nearly as much as I would have liked to. On one of the occasions when I did bring it out, the brake master cylinder had gotten so low that I ended up with air in my brake lines.

No big deal. I bled the brakes, drove the car to work for a couple days in a row just for the hell of it. But I noticed something that I don't think was happening before. If I put any kind of sudden pressure on the brakes, not really an emergency stop but more pressure than if I was normally approaching a stop sign, the brakes lock and the tires screech and slide on they road.

I'm talking about low speed situations where the guy in front of me has decided to stop suddenly to make a turn, so I put my foot on the break and it locks!

My instinct is that I didn't bleed the brakes properly/fully and there is still air in the lines or something is worn. I had a Duster back in my 20s and I never had this problem but I did have other problems that required me to replace essentially the entire breaking system. So I'm not afraid of getting my hands dirty and fixing whatever might be wrong.

But I'm also wondering if I'm just rusty. Have I been spoiled by ABS systems for the last 20 or so years? Maybe I just don't remember how to drive a non-abs vehicle properly? I mean I know I have to pump the breaks in a sudden stop situation, it's just not instinct anymore.

So I thought I'd come in here and ask people who have more and more recent experience driving these older vehicles.

Which do you feel is more likely?

1. There is something mechanically wrong with my breaking system at the moment.

2. The car is fine and I don't have that magic touch for breaking in a non-ABS vehicle anymore and just need practice.

Obviously there is a third option of both, and I will admit I am out of practice I just don't think it was doing this before. I feel like I was able to apply a moderate amount of sudden pressure and gradually slowdown like normal. Now, I screech to a halt.

Cast your vote!