possible electrical problem?

[84lwb]

The other night I was showing off my truck to a freind of ours son.All the sudden the gas guage and the blower motor started working.The gas guage only worked the fist time I fired up the truck,since then it's been pegged past full,and the blower has never worked,but when I flipped the switch it came on,but only on high speed and to be honest it doesnt feel like its blowing as fast as it should but it is blowing.any ideas as to what I should look into so this thing doesn't catch fire,thats the last thing I need right now!