you might want to post your year and engine size. I think the mid 90's Rangers and newer did not have the TFI problems.
When my 87 Mercury Grand Marquis had the TFI go out, the symptoms were it ran great, no problems going to work, and when I came out from work it would not start. the starter turned the engine over no problem, but no spark.
Was not hard to change, I needed a 1/2" ford distributor wrench and a TFI wrench. took about 15 minutes maybe..
AJ