86 supra problems

[dom747]

hi, i bought a 86 supra with the 7MGE non turbo engine, the car is in pretty good shape, but has some problems,...the car has been sitting for a while, when i first went to pick up the car, i started it up no problem and it was idling fine, when i was just about to leave i noticed that it was nearly out of gas so i took some gas and put it in, when i went to start the car up it wouldnt idle, another problem is when i got the car home i noticed the temprature was way up, i topped up the anti freeze but it would still get hot, inside the car it wont heat up when the heater is on. another problem i found is that the guy who owned it said that it has a head gasket blown on it, there is a oil leak but it is coming from the valve cover, is the head gasket difficault to change?, another thing i noticed is when i had the car running and just played with the throttle to keep it running at 700rmps i noticed that the oil pressure would go down but when i reved it it would go up a little, is that normal, and what should the oil pressure be at?..