i have 1 90 with 5.0, been having major problems with the engine cutting out while under load, i got a map sensor, and 02 sensor code, i unpluged the 02 sensor and it didnt run any better or worse. could the 02 sensor be the prob? should it run differently if its unpluged?

 

Try disconnecting the connection to your MAP sensor. See what it thinks about that. (leave the Vac line connected)

 

Like Ski and Sean say..The o2 sensor talks directly to ECU and is VERY Important..I was smelling fuel from exhaust when idling and mileage was bad..I changed out the sensor and now truck idles even better than before and I no longer smell Gas in the exhaust like I did before. I suggest you clean the IAC Valve and check voltage on TPS..if bad replace..(10 Min job at 23 bucks.) The IAC Valve can be replaced..but it's like 70 bucks..easier to clean it..and 70 bucks cheaper. Might Seafoam your motor while your at it..easy to do and dont forget to add some to your Gas and Oil as well..Add to Oil a couple hundred miles before your change is due..

BTW I dont think unplugging the O2 sensor would make any difference..other than giving the ECU bad info...

 

if i unplug the map sensor the idle goes up, if i unplug the vacume line it will die. also it runs fine till it warms up, but has a very fowl smell not like gas though

 

iac cleaned, tps replaced, cleaned throttle body, and replaced plugs.... same problem getting ready to sell the thing

 

Try removing the o2 from the bung hole. Leave it connected & hang it off something if you can. See if that allows a load on the engine. If that does, your Cat is clogged.
Also, I believe Manifold Vac pressure takes a big dive when RPM is increased, if a back pressure condition it present (w/ the o2 in place)

 

just an update incase anyone having the same problem see's this thread. the problem was the fuel pump, it must have not been pumping enough, replaced the pump and it runs great again.