2004 impala stumble and hestitation

What is your question?

2004 impala slight hesitation on take off sometimes and sometimes engine stumbles on decell other than that runs great plenty of power and getting good gas milage tps iac igm fpr coils plugs wires and lower intake have been done when it does itt on highway with scan tool can watch rpms go from 800 to 400 back and forth

What makes this problem better or worse?

cold

How long has your 2004 Chevrolet Impala had this problem?

More than a month