If it feels like you have misfires, then you should probably first start with changing your plug wires and spark plugs. Make sure you go with the proper plugs and they are gapped properly. Also, NGK's are a good brand to go with, check out their website they have a parts application list. If the ignition tune up does not solve your problem you may have to check into your distributor (if you have one) and test your coils..
About the tapping, that sounds like maybe your lifters, try throwing some Marvel Mystery Oil in your oil to see if it helps. If it does help then your lifters are noisy and eventually they'll need to be replaced..
1990 Ford Probe LX 3.0L V6 :s6:
SEE IT HERE:
1989 Mazda RX-7 Turbo II 13B-T "FC3S"
Turbo RWD Rotary Powa!