Please help. 91 nissan maxima GXE engine miss

Hey everyone,

First of all, sorry for the cross posting but I believe it's relevant
in all groups posted to. I have a 91 nissan maxima GXE with 190k, V6,
5sp. This car has driven great until 2 days ago. All of a sudden
(literally overnight)it developed a miss that is noticeable throughout
the entire RPM range. Car ran great Friday and then Saturday when I
started it, the miss was noticeable. The idle is down to about 600 vs
800 it was before and power is down. I checked the plugs, wires, cap
and rotor and they all look good. They are about 2 years old with
roughly 15k on them. The miss seems worse when the engine is cold. I
can't see any wires arcing and have verified that there is spark at
every wire using a timing light. The check engine light is not lit.
The car shakes mildly at idle and has kind of a pfft pfft sound at the
exhaust pipe. Anyone have any ideas on what else to check? I am at a
loss and need to get her running right again asap.

Thanks in advance

Derek