My Father owns a 2001 Ranger and asked me to test drive it the other day. It is the 4 banger auto completely stock with 80k miles on it.

He said that it cranks fine, no codes thrown and runs ok until you get on it. It absolutely falls on its face and will not accelerate.

He had a tune up done about 1,000 miles ago ( 4 months) and this is when he started experiencing the sluggishness.
Tune up consisted of 8 new spark plugs ( 4 intake , 4 exhaust) new air filter, fluid change in radiator, tranny and oil.
The guy did not change the fuel filter.

After driving it and experiencing it for myself, I immediately changed the fuel filter...it was bad!!! nasty black with silt all in it.

It did help it some, but the issue is still there.
Do you think that the fuel pump intake could be clogged?

Whatever it is , it has not thrown any codes, but the truck is having serious issues when you press the pedal down quickly to accelerate.

Thanks for any info / advice

Mike