Please bear in mind my experience with intercoolers is limited to one example on a Peugeot 306 Turbo Diesel!
1. Did the power/smoke problem start when the intercooler was fitted? I would be surprised if there was any connection unless the garage damaged something else while they were fitting it.
2. Why did the intercooler need replacing? The 306's intercooler has no moving parts, no water seals and minimal air hose seals. It would only need replacing if it had completely disintegrated.
3. Haven't all Mondeo 1.8TDs got no power when cold?
4. If it's nothing to do with the intercooler, you are back to standard diesel starting problems, usually glow plug related, possibly injector problems (not so common) etc. Search this site for "diesel start smoke" - there are 228 hits and I bet one of them has your answer.
It sounds like the cold advance device fitted to the fuel pump is the culprit. This device changes the timing when cold to give optimum power and emissions. It could be stuck in the hot position. The Lynx engine fitted to the Mondeo is a bit smoky when cold if the fuel governor needs adjustment. I'd take the car to a good diesel specialist (not generally a Ford dealer!) and get the fuel injection pump checked over.