i need help i have a 97 f150 with a 4.2v6 it lacks power at warmup misses constantly and runs rich carbon on my tailpipe i pulled the plugs there black carbon fouled it surged for a while so i put a fuel pressure regulator which fixed the surging but i still cant figure out why its running rich and looses power when it warms up i cleaned the throttle body had both upstream sensors and down stream sensor replaced put new wires on it new plugs had a new coil pack installed i dont know where to go from here i hope someone has info that will help me with this problem any info will be much apprecitated

thom
1997 f150 4.2
styleside
gibson exhaust
hypertech power programmer3

 

possibly the throttle position sensor. I had that problem once on my mustang. Could be it.

 

anyone who wants to keep tabs with 4.2's
did your 4.2 do this before or after any mods?

 

How many miles are on it?Did the check engine light come on?The 4.2s do have a tendancy to get a buildup in the upper and lower intakes if you spend a lot of time with the petal to the metal.I doubt this is the problem though.You would just lack power all the time.Running rich...it could be what Svtoby 150 suggested.I wanna say take it to the dealer and have them see if the computer is throwing a code(or buy a code reader thing),if it is they will be able to tell you the problem.Good luck and keep us posted. I am curious about what the problem is.