Need help with an original challenger r/t, asap

Take the fuel pump out and check it out. Look at the timing chain through the fuel pump inlet and see if you see any fresh "scrub" marks on the chain anywhere. If you can't see the chain directly then use one of those little mirrors. It could be numerous things but taking the timing chain cover off you have accomplished a few things. You check out the fuel pump,timing chain, harmonic balancer, oil slinger, timing chain sprockets, water pump etc.. This is what I would do.