Be honest I need help

So i have a 2004 ford expedition. 5.4 L.

It has 170,300 miles.

It has a misfire, not caused by the ignition coils or spark plugs as I have replaced them twice.

The injectors are fine.

It is the lifters.

I was quoted 2,000 - 3000$ to repair it.

Is it worth fixing or do you think I should just cut my losses and get rid of it .

It still drives but obviously misfire and runs like shit.

How long do you think I can drive it for?