1998 Plymouth Voyager check engine / misfire

Ok, failed emissions due to OBD failure with random misfire errors. Did tuneup. Plugs wires cap rotor air filter. Reset ecm at the autoparts store. Drove for 50 ish miles, actually passed emissions test but still have a miss and light came back on. Some one told me possibly a bad coil but I always thought a coil was either good or bad, not intermittent. Maybe injector? Ecm? Any suggestions as to what parts to throw at the poor thing. Runs okay if you don't mind a miss. Mostly at idle in drive. Also always has a tick like a lifter when cold.