1991 Dodge Dakota 193000 miles, 318, 4X4
Original transmission, original engine.

Idle is fine, engine purrs like a kitten when driving. Can't tell if my problem is engine or transmission.

When I am driving a constant speed and let off the accelerator slightly to slow. or I am running a slow speed 40 or below I get a slight surge or loss of power maybe. it almost feels like the tranny slips for an instant. I am baffled. EGR system checks OK Fuel pump is relatively new, fuel pressure regulator changed when fuel pump changed. Injectors less than 1 year old. throttle body cleaned when injectors changed. tps changed within 2 years. vacuum @ idle is around 18-20. map sensor relatively new.

any ideas

thanks in advance

 

As an FYI, truck has been fine for some time. none of the changes listed above were done within the last 4 months or so... problem is a recent development...

 

Any ideas guys?

 

To me it sounds like the torque converter lock up clutch.