2000 Ford Ranger Extended CAB 3.0 Engine Question

I have a Ford Ranger that has been acting up after having it at a local Ford dealership for an oil change and some repair work. It actually seems to be worse now than before taking it in. The mileage on it is 92,000 miles. The oil pressure gauge jumps around every time I drive it when slowing down & when shifting from first to second. Also the entire vehicle is getting very very hot after having driven it even the rims and the metal rod that props up the hood! It is making several odd noises while driving it. And I am losing a lot of coolant from driving it, more than could be a normal amount. The technician at the Ford dealership checked the oil pressure, but couldn't find a problem. What is wrong with my vehicle? Any help would be appreciated! Thanks in advance!