I have a 1984 Ford F150 with a 5.8L 351 that I just purchased and have only been running for 3 days now. I noticed that it was idling very high when in park but as soon as I put it in drive or reverse the idle droped to what sounds normal. The guy I bought it off of had told me he had a new carburator put on the truck. But when I am driving the truck and after I get it warmed up (about 20 min.) It starts to idle very slowly and is barley running and the oil pressure gage drops to the lowest it will go and now I noticed that the truck is getting very hot (almost to the H on the meter) when I am driving it. Why is it doing this? Could it all be becuse of the carburator in the truck?