My engine has been sputtering a bit. It seems to only do it at highway speed, under load. It's like it just drops out for an instant here and there.

Also, a few mornings after my truck has sat all weekend without running, it will take a lot of cranking to start it. If I jumper around the COR so I can let the fuel pump run a few seconds before starting, it starts up fine every time. Jumpering around the COR has no effect on the sputtering. Cold start stuff is good, TPS is good.

Theory: My fuel filter, which as far as I know has never been changed, is cloggy and isn't letting fuel through it fast enough to maintain adequate supply for climbing grades on the highway or for starting cold and dry.

Possibly related symptom: My truck has always had a ping on the highway while under load, basically showing up under the same conditions and about as often as the sputtering, unless I retard the timing a bit and run 91. Maybe the filter has always been kinda bad and causing a lean ping here and there.

I think I'm going to buy the filter from Toyota and have a mechanic install it. It's cold out and it looks like a pain in the ass. Thoughts on the diagnosis or on supplying the part to a mechanic?

 

It is a PITA. If it is like mine, it is on the pass frame rail, and is stuffed behind, up and underneath. You need a crows foot wrench to loosen it, and you will definitely have bleeding knuckles and many cuss words breaking loose. Best $35 I ever paid a mobile mechanic! You may want to start spraying the bejeebers out of it to loosen up the corrosion on the threads, using PB Blaster.