[2-77s, 1-85, 2-86 TCs]

I just bought an '86 Thunderbird Turbo Coupe tonight. I have to pick it up soon, and the guy said I can fix it at his house when I go to pick it up. I'm driving it back, so I need it to be road ready when I'm done with it. So I have a question. This is what the guy told me: When you first start it up, and the engine is cold, it runs terrific. But once it starts to warm up, it runs rougher and rougher as it goes. The longer it runs, the rougher it gets. What does that mean???!!! It's got something to do with the engine. I'm hoping it's just a tune-up, but I'm not so sure. Somebody told him an oxygen sensor. Someone else told him a turbo sensor of some sort, and somebody else told him the turbo was bad. If anyone could PLEASE help me out, it'd be greatly appreciated. I've been a mechanic for a few years, but I've never messed with a 4 cylinder, and especially not a turbo engine period. Thanks in advance.

Rick