How to fix Squealing ram truck belt?

I have a dodge ram 1500 v8 it’s a 1996. Well I replaced my belt and tension pulley thing and that worked for about three weeks, then a storm hit and the squealing has returned. If I’m not revving the engine or keeping rpms low it does not squeal or very little but the second I touch the gas pedal bam super loud annoying noise. What can I do? I don't have money to pay mechanic to sit around for hours, so trying to fix in house. Also I was told might be idler pulley but no clue which one that is.