I have a 5 spd manual transmission 1993 Ford Explorer Sport 4WD, V6 4.0L, 170k miles. Towards the end of last week if started feeling under powered. As I started my usual shifting into gears it seemed to chugg or sputter to gain speed/rpms. This chugging seems to also occur even when running at steady speeds down the highway, as if the suv is surging, then not.

According to Edmunds.com, known issues with this model are:

"Occasional problems on this vehicle are failures of the Fuel Pressure Regulator, the Mass Air Flow (MAF) Sensor and the Intake Manifold Gaskets. Failure of the Fuel Pressure Regulator may prevent the vehicle from starting."

I eliminated bad gas being the issue since this started with a 1/8 tank left before I refilled it.
I would guess if its bad cylinder or compression issue that a code would be thrown

I brought it into Meineke Car Care Center nearby yesterday. They told me no codes are being thrown and everything was coming out fine when they ran a full diagnostic. They said the plugs/wires seems to be operating properly as well. They replaced the fuel filter in case that was the issue, apparently it was pretty black. They also cleaned the Throttling Body as well.

I drove it to work today and could still feel the chugging/surging happening.

Any help/suggestions would be appreciated.