Hi, new member. I was given an 07 f150 by a former co-worker. It blew the trans line at home and he noticed it right away, thank Jesus. Anyway I got the truck home put all new trans lines on it. I drained the old gas. The truck had a new or rebuilt engine put in right before sitting for 3 years. Anyway it runs like dog**** I'll figure that one out but in the meantime does anyone know the purpose of this little black thing. Green with red stripe into this box which is then grounded to the engine on the front driver's side.

Dead center with rust bulging out?

 

If I am seeing the correct thing I think it's a noise suppression capacitor to prevent the ignition system from making electronic interference with the radio, etc.
https://www.tascaparts.com/oem-parts...hoCYB0QAvD_BwE

 

Yep noise capacitor one on each side . If its shorted it will cause ignition failure . It can be checked with a good meter that measures capacitance . If bulged it must be replaced . That one is certainly bad .