I put my car in drive and went about 25 yds and it's like the brakes would lock up I can put it down in the lowest gear and it will drive just not over 40 mph and the rpms boug down what's wrong

What is your question?

It just started all of a sudden not gradually. Had some issues when I first bought car used with it not holding brake fluid and I got that fixed. It will only drive in lowest gear without the brakes locking but the Rpms are high and it's like you have to floor the gas when you hear them starting to drop so the car will not shut off. Can't drive over 40 mph.

What makes this problem better or worse?

It’s worse when it’s hot and I haven’t driven it much but when I did it was from point a to be

How long has your 1999 Ford Mustang had this problem?

A few weeks