Fuse #30 keeps blowing (speed control)

I just got a 95 Windstar and had the motor swapped out in it (3.8 litre). This was done by a professional shop, and it was a direct replacement. Nevertheless the speedometer had stopped working right after I got it back from the shop. I later found that the problem was that the cable had come loose (probably didn't get plugged back in tightly during the motor swap). While I was searching for the speedometer problem I noticed that the #30 fuse was blown, which was a 25 amp, and it keeps blowing the replacement fuses. What might be the problem? Could the speedometer cable having been loose been the original cause of the first blown fuse? I ask this because I haven't been able to go to the parts store for another 25 amp fuse yet, so I tried a 15 amp which might not be big enough. Any ideas? Thanks.

I'd replace it with a proper 25A fuse before jumping to other conclusions. That fuse may simply have been blown when all of the engine work was done; replacing it may be the solution.

The only thing the blown 15A fuse proves is that this 25A circuit draws more than 15A.

Of course, to be safe, be sure to buy more than 1 25A fuse!