Although there are now some paint manufacturers who claim that they have paints that can be used successfully over plastic laminates, our experience suggests otherwise.
Due to the dense composition and non-porous finish of plastic laminate, paint will not properly adhere and will usually end up chipping and peeling. This is especially true of horizontal surfaces such as kitchen countertops that get a lot of use.
Your best bet is to replace the countertop with a new one or install ceramic tile over the existing top. You can reface the laminate cabinets with a new laminate or wood veneer and install new doors. That should help make your kitchen more mellow than yellow.