Hi,
having the same issue on my '99 Amigo HT V6 4WD. Also seemed like my alarm wasn't responding sometimes but I thought that was just the remote battery. Actually mine has gotten worse as it started out with your symptoms and now has progressed to where my dash lights and rear lights don't work (brake lights and some of the dash indicators like gear still work).

I found the 15A fuse for "Tail/illumi. Light" busted, so I replaced. Once I did this all the lights worked again and so did the rear wiper - for about a minute. I tried it with the radio off after a replaced with a new fuse again, same result, it works for a minute or less and then -pop. I installed my own stereo, speakers, and sub a while ago and all has been working for years and then suddenly this. Even without replacing the fuse all the stereo stuff works - just not the tail lights, rear wiper, and dash instrument lighting.

Does anybody have any suggestions before I take it in to have it looked at?