can't seem to fix this problem

[berryn]

Anybody who know anything about this or is experiencing the same problems please reply.

I have a problem where my truck will runrough and/or stall. THis seems to happen at the lower speeds and never happens on the highway. It is most noticable when i'v come off a highway or freeway. But it will happen in the city as well. It happens at any throttle position.

I have replaced the tps,maf,egr,fuel filters, fuel pumps, cap, rotar, plugs, and wires. Also have cleaned the throttle body and the throttle bypass valve. Have pulled the code and am getting 41 and 33 wich are eog sensors reads running lean and erg valve not opening. I have checked the erg valve and it works. I'm not getting and vacum to the egr valve for some reason and the vacum lines seem good. my only thought is that it may be the map sensor. any suggestions?

[berryn]

it is a 87 ford ranger 2.9l 2wd

[Stevo2]

berryn, we need to fix those codes first before moving on. The book says replace Oxygen sensor every 60K and if the sensor is giving false info to the computer that could cause air/fuel mixture problems. It may also be that the EGR valve circuit malfunction may be contributing to the O2 sensor code/failure. Lets try to get rid of those codes first. Did you clean out the manifold ports under the EGR valve when you replaced it? Was there any type of sensor attached to the top of the EGR valve? When you follow the vacuum line back from the EGR valve check to see if there are any small plastic connectors inline, if so this could be a restrictor or filter. Have you tried to disconnect the vacuum source to the EGR, plug the line and run the truck to see if any difference?
Couple more possibilities for the stalls/rough idle. The idle air bypass valve could still be sluggish, it must react instantly when you release your foot off the accelerator to provide more air flow as the throttle plate is now fully closed. It must also respond when you press the pedal down. Fords have a long history of sluggish air valves. Just some thoughts for later. Lets fix the other 2 codes first.:bandit: