I have a 2000 toyota 4 runner sr5 4x4 v6 and we did an rngine swap about a year ago for a motor out of a 2002 and it has been running gear now all if te sudden it wants to sputter and ˟˟˟˟ down when I pull up to a stop sign and sputters when I take off once I take off it runs fine but as soon as I let off of te accelerator it starts sputtering again I do not know what to do can someone give me some input. I do not think it is plugs or wires since it only does it when idling.