Rough Running 91

From: Rapom66@localnet.com
Date: Tue Dec 03 2002 - 22:11:55 EST


Hi DML, I just signed up in the hope that one of you could help out a fellow
Mopar enthusiast down on his luck.....
I have a 91 Dakota, 2wd, ext cab, 3.9 Throttle body EFI that does not want
to run smoothly just off idle up to about 1400 rpm. This is most noticeable
under slow acceleration or unloaded (neutral) If you accelerate rapidly you
do not even notice the problem. Once you get past 1400-1500 rpm the motor
smoothes right out and runs excellent. The problem seems worse during cold
weather. In addition to this my fuel economy is off by 3-4 mpg.
The motor is orig. with 140K on the clock. I replaced the timing chain &
gears at 110K, I recently replaced the coolant temp sensor and throttle
position sensor neither of which seemed to help. The EGR valve is in good
shape, not plugged and appears to be functioning corectly. The truck
received a full tune up 4 months ago (everything) including O2 sensor. I
have searched & searched for vacuum leaks but have found none. I checked the
computer using the key & check engine light method and it is not holding any
codes.
I am stumped.... I have been rebuilding old Mopars for 25 years and have
never yet paid anyone to fix on one of my vehicles. I refuse to let this be
the first one...
Any advice you can offer would be greatly appreciated.
Thanks, Paul S.



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