Do my symptoms point to a future engine problem?

I bought a 95 2wd, chevy astro 2 weeks ago.
I checked the car, the oil was clean, and everything is ok. I liked and
bought the car.

The previous owner told me he bought the car 2 months ago, with an engine problem. He had the crankshaft and some of the push rods changed. He drove nearly 80 miles after repair, and sold it to me.
I bought and start driving. The engine was strong. But after 50 mile, I
notice the engine misses lightly. I checked the spark plug wires and notice #1, 3 and 5 wires are burnt in some parts. I changed the wires and now it is missing hard on #3. At the same time, I start to feel that the engine is not as strong (This is my 3rd astro/safari van) as it was the day I bought.
At the same time, I start to get an oil leak. It is coming from oil filter adaptor. As I start to work on this, I notice the oil is extremely dirty. It is not old like any oil after 3000 miles or brownish muddy like if you had a head gasket problem. It is not transparent and I feel like it has many shaving in it.
If I'm right to worry about shaving, is it normal on new crankshaft or am I killing the engine.
TIA, Ulas.
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No a new crank will not shed metal shavings.
I don't have an definite answer for you but you should always worry about metal in the oil. As far as the dirty oil, I had the intake gasket changed in my suburban and it took three oil changes 50 miles apart before the oil stayed clean. Opening a old engine stirs up an amazing amount dirt in the engine. So I bet the black stuff in the oil is probably soot but I would get a strong magnet and see if any of it is iron/steel. Also put a little of the oil on your finger and see if it sparkles in the sun light when you rub your fingers together.
If you can afford it I would take it to a good mechanic and have it looked at, not because of what you suspect but the fact that the previous owner put that much money into it then immediately dumped it. If you can't afford a mechanic then I would immediately change the oil and get yourself a compression tester. Did the PO specify what the engine problems were (I.e. a bad oil pump) that caused it to eat a crank and push rods...
See what others say...
good luck, mark
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-------------
SNIP.
"Some pushrods"...?
Holy cow... and the crank?
What I'm about to say is not in anyway directed to you. Your previous owner is:
A.) Lying his ass off. OR B.) A complete idiot.
The amount of work to pull that crank out is allot. Not rebuilding the motor FULLY at that point is the most ridiculous thing I've ever heard.
You can play with it, but it needs a proper rebuild... if it was mine, I'd yank the motor, and buy a long block crate motor. It'll be way cheaper in the long haul.
HDS
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The symptoms do not point to a future engine problem.
The symptoms point to a CURRENT engine problem.

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