OBD-1 code help please

[CONavajo]

I just did the paper clip test and it looks like code 41 is the result. The chart says it is a fuel system problem, running lean. Does anyone know what to do to remedy this? I thought it was running rich but now I am not sure. Here are the driving symptoms; bad mileage, lack of power, hesitation on acceleration, rough idle and surging RPM's at low speed or idle. THis just started yesterday and I had planned to wheel on Mem. day but now I am not sure. It also seems to be running a little better this afternoon. Can anyond offer any advice? I did just drive from Nebraska to Vail at 8000 ft. and it started acting up just outside Denver in the foothills. I have done the drive lots of times though. Could it just be a fluke thing with the altitude change? I am thinking about disconnecting the battery and letting it reset itself, could this help? I know this is long but since my Navajo is my only vehicle I need it to run good. Thanks in advance.

91 Navajo LX
5.5" lift, 33x12.5 KO's
4.56 gears, Truetrac

 

[mdrut]

Does it puff black smoke when you floor it??? Sounds like the fuel pressure regulator or T.P.S.

 

[WorkTeke]

O2 sensors?

BTW, is there a test that tells if the sensor is fine, going bad, dead etc.