We have code P1518 on our 2002 v6. Already replaced the clips to reattach the arm that was off and manifold gasket. Check engine light went off briefly after disconnecting the battery for awhile, but is back on

 

If it's not the arm clips, then you're talking four other things:

The arms can't move the butterflies in the intake, possibly. Take the clips off and ensure the arms can move the butterflies. If the butterflies can't move, you're fixing that first.

Next is the wiring to the actuator, and that's just a check you'll have to endure. Wiring check isn't fun.

Of course, the actual actuator could be the issue, and yes, that is a replacement part you'll have to source. Lemme just check the pricing on that... *chokes on drink, spits it out*... Um... ow. Pretty expensive for a 'maybe'. You might go to a junkyard and pull one off of a donor instead, hoping you get a 'good' one before you get that $150-200ish part.

And if you replace it, what you hope is at this point you're done and it's now working correctly. Because if it's not, then you're down to the computer being faulty, and that's not going to be fun...

It's not going to be the gasket, that's a whole other set of codes.

Hope this helps. Good luck!