95 rodeo knocking sound on top of engine

just got 95 rodeo with 172K miles on it and it sounded great on way home. Since then have changed oil, washed out the engine compartment and filled it up with gas. Suddenly, there is a weird sound coming from engine at idle and low speed that goes away when engine is revved.
One thing i noted when changing the oil. it completely filled my drain pan overfilling and when i added oil back in, it only took 5 quarts until it said was full. I know i drained more than 5 quarts out of it. I also put in some fuel octane booster thinking the knocking was from gas.

I dont know what to do now. suggestions?

just got 95 rodeo with 172K miles on it and it sounded great on way home. Since then have changed oil, washed out the engine compartment and filled it up with gas. Suddenly, there is a weird sound coming from engine at idle and low speed that goes away when engine is revved.
One thing i noted when changing the oil. it completely filled my drain pan overfilling and when i added oil back in, it only took 5 quarts until it said was full. I know i drained more than 5 quarts out of it. I also put in some fuel octane booster thinking the knocking was from gas.

I dont know what to do now. suggestions?

172K miles + tappimg/knocking sound that goes away as RPMs increase = bad timing belt tensioner

when i got my timing belt tensioner the tik was notNEARLY as loud as the KNOCK from needing a new timing belt tensioner. and my tensioner still made the sound until i got past 2,500 rpm's. the tick is constant but sometimes more faint than others.

Thanks for the info. I will get that checked out and let you know if that fixed it for sure.