It was running ok, now it’s terrible, I need help!!!

Turn the crankshaft back and forth with the distributor cap off. See how far you can move the crank until the rotor in the distributor moves. That is your chain slack from the nylon teeth coming off the top timing gear. I believe you need a timing chain.

Also pull the oil pan and clean the oil pan pickup screen . All those nylon teeth will be in there. Not cleaning them out will be the downfall of the engine when it loses oil pressure. Very common on slant sixes