I have a 1990 suburban that has had a rebuilt x-mission about 50,000 miles ago. At this time when I drive there is a hesitation, split second, when running on flat road. It happens when going up a hill, too.
My mechanic said change the: plug wires, then the plugs and rotor. No difference.
I think the thing is dropping out of OD for a split second and then going back in. If I drive in 3rd, I don’t think it is happening. Isn’t there a relay or solenoid that controls this function?