My dad gave me this car, and I'm having problem after problem with it.

First the started had a BIG flat spot so we got a new one.

Then a exhaust manifold bolt the on passenger side broke, replaced it. (had to fix a major exhaust leak).

Then it was okay for like a week, alternator went out on the way to school. junk-yarded a like brand new manufactured one.

Fine for another week, then the fan on the radiator poked a hole in it and it started leaking behind the block too. Some Stop-Leak fixed them.

Another week later hose from water pump to radiator had a massive slit in it, replaced it.

Now it's been running okay, not good but not bad till 3 days ago. It used a HALF a tank of gas going 6 miles(within the two days). It's been skipping and we can't figure out why it has:
brand new 8 spark plugs, all new wires, new disturber cap,

and it's still skipping really bad. When I start it up, it is at 1500rpm in gear then after a mile or so it idles 400-700. Today we replaced the TPS and it is running better but not the best.

So I have three questions.

1. Why do you think it is skipping?
My dad says I'm using "to good of gas" because he ALWAYS put 83 walmart in it and i'm putting 93-89 Chevron.

2. The other is my (might help answer the other) oil pressure goes CRAZY, it starts with 30 after I drive it for like a block it will start going down and fast to about 10 then i press the gas or rev it up and it will go to about 30 sometimes more or less. Other times it will stay at 30-55 for thirty minutes then get low.

I did a lot of research and I ask him it was the mains, bearing or ____ (<-- something like the mains, it was just on the tip of my tongue)

He was like no, the car isn't smoking or rattling or anything.

3. What size thermostat should I have in the car?

I think it had a 160* and he replaced it with a 180* near October last year so he would be cold when he was driving it.
I put the 160* back in it and I told him it's running better but he was like the 160* will mess the car up because it's "Always" ran 220 with him, and it's running probably 180 top with me.


Sorry this is so long and stuff, Any and all help will be thanked a lot

 

yea, what did set the tps too voltage? 91octane or higher only, because its high compression engine, did you change the oil? 10w30 castrol and a clogged oilfilter would hurt oilpressure. its needs at least a 175* tstat. i like 180*. with a 160* the computer wont go into closed loop. A lot times rich conditions is the computer being in open loop. things that affect the computer are o2 sensor, coolant sensor, timing, tps. you can test the coolant sensor. a lot of problems with rich condition are from coolant sensor. the car thinks its 0* outside all times.. but ditch the low octane gas for 91 or greater for sure.