i have a 1987 7mge supra and i was having starting problems, at first it would like never start maybe like once every other day, i changed the spark plugs, spark wires, igniter and coil pack, oil, and battery and i ran injector cleaner, now the car starts but i have to crank it for a while and press the accelerator a couple times to get it started, after its started the oil pressure rises and it goes up to 3k then slowly comes back down till stock idle than every now and then it will drop to like 500 rpm and start to bog a little. What could cause these things?