Truck Repair: ford explorer fuel issue, mass air flow sensor, mass air flow

Question
my 1996 ford explorer 4.0 six cylinder engine, has been giving me problems recently. upon start up after about a min. the engine starts to rev up and down while in idle and if i put it in drive it continues to rev up and down and cuts off.  there's black smoke coming from the tail pipe. ive checked the m.a.p. sensor, vacuum hoses, cleaned the i.a.c. and changed the fuel pump but all to no avail.  any suggestions?

Answer
Hi Travis,
I have had similar symptoms with my explorer when the air filter is out or the mass air flow sensor is unplugged...kinda sounds like an old muscle car? look for a leak in the intake ducting, check specs for the mass air flow sensor, check for any vacuum leaks.

good luck,

Matt