2000 T&C with 3.8, 201,000 miles. Yesterday noticed poor tranny performance, sluggish, chugging off line and chugging in reverse. Audible hissing at lower injector o-ring on rear driver's side injector. I sprayed the base of that injector with carb cleaner and hiss stops and idle drops. I think this is source of tranny issue as it's a brand new tranny with about 10,000 miles on it.

Can I change the seals without removing upper manifold? Seems hard to get at the injector clips with manifold in place. I know sometimes you need to lightly tap the fuel rail with rubber hammer on a block of wood to get them to seat in the manifold. None of the injectors are leaking and she runs like a top otherwise. Should I change all injectors while I'm at it? Any tips on the intake manifold gaskets?