Hey everyone

I know I am new to this forum but I need to get everyones advise on this.

I have a 1996 A4 Quattro V6. It has 161,000 miles on it.
We bought it from a previous owner. They had the engine replaced from a junkyard at 138,000 miles on it. The engine had 98,000 miles on it. It has been running okay, but all of a sudden. It started to run rough and idle hard. I just recently changed the spark plugs and wires because they have about 60,000 miles on them. They are the correct spark plugs and wires and everything is in good shape. The engine turns normally and the car is getting fuel.

About 10 minutes before it started running rough we filled up with gas and we used 91 octane. Now it will not even start.

What are the chances of any issues you guys can think of.
The cars compression is cyl #1 120 #2 98 #3 95 #4 98 #5 90 #6 115