bad sensor!! but which one??

When it gets cold like around 20 degrees I will try to start my 93 ranger V6 4.0L. What will happen is it will run for a few seconds then just die, but if I press on the gas far enough it will run (sometimes hesitating and choking out). while I got it at about 4000 rpms to keep it from dying it blows out a lot of black smoke. It sounds horrible when it idles and is driven. I'm pretty sure it's a sensor but I'm not sure which one. this normally only happens when it's that cold too. when it's warm everything runs perfectly.

Also if it helps I think it started doing this after I washed my engine with cold water when it was hot.

Had a bit of problem with my last two replies. Seemed like they did not go through. Nonetheless, I'll try again.

If '94 Rangers are anything like '99s, the Power Control Module (PCM) remains at a default setting after a cold start. After a period of time based on engine temperature it enables and start to function based on the various inputs. Thus the O2 sensors although suspects don't come into play until later. With your description regarding the black smoke which is an indication of overly rich mixture, the PCM is starting to become the prime suspect however, before concluding on that, check out other components such as the engine temeprature sensor (not the guage sensor), MAF, ICS, EGR, etc
Are you sure you are not getting any Check Engine Light indication?

yes the check engine light does come on when this happens.

Can you get a hold of an OBD and extract the code/s? It will help a lot. I understand that Autozone allows one to borrow. the let us know.