Couple of questions.

1. How often should spark plugs be changed on a 1998 F150 with a
4.0 liter engine?

2. Drivers side window will not go up or down. I can hear the motor
run in both directions (up & down) but window does not move.
I can pull the window up and down with my hand. Is this a motor
issue? I had the motor replaced 2 yearS AGO.

Thanks

 

Idk on the spark plugs but as for the window it sounds like it's off track

 

Plugs are one of those things that can be changed and checked by almost anyone. I have always liked to switch plugs at no more than 50K. So many manufacturers say theirs will last 90 to 100K but they will tell you oil can go 7500. They are a relatively cheap way to bring things back to spec. The one thing I would also do is change the plug wires at the same time. Wires are subject to heat and often fail before the plugs. Always buy the best wires you can afford when you install a quality plug.

 

For the door I'd rip
The door skin off and look. I have a motor half burnt out in mine that doesn't move the window anymore(or moves it very little) that can still can be heard.