hard to start on 1993 Mazda B2600

pickup is hard to start on rainy days. changed rotor and distributor cap but no help. what next?

Asked by for the 1993 Mazda B2600
Really the whole tune-up should include the wires, plugs cap and rotor as well as the air filer and fuel filter and a timing re-set. If those are in really good shape, then check the coil, make sure it is really strong and then check the codes for a sensor being out of range.