tuning

[njw]

Before I pose the question, I am a novice in the mechanical department.
Q: Why is it that when you have a car tuned (not just TVR), they come back driving like a dream but soom revert back to prior tune up?

[njw]

Had an escort tuned a few years ago, came back great but soon went back to usual. Same with a Granada 2.8 way back 10 years or so.
The S drives beautiful one day and the next it seems not so smooth through 1st gear, ie, you have to think about the throttle and clutch rather than just going into auto pilot mode. Don't get me wrong, there is nothing wrong with her, she's quick, noisy and fun (a bit like her in-doors). Perhaps I'm just a fuss pot?