im still having probs with my 93 300sl, it has trouble starting when its cold then when it does start it has to sit running for a few mins before it will rev up ... i changed plugs, wires, fuel filter , and ordered cap and rotor but i dont think thats going to help .. i only have 50k miles on it so it shouldnt be anything serious .. any ideas .. also where do i hook up a fuel pressure tester

A cap and rotor could help if the contacts are badly corroded as is pretty common on the caps.