Sounds like they are carboned in. I had to destroy mine to remove them.
So I gambled and bought Mustang injectors from 5-O motorsports and I am
very pleased.

The Mustang injectors are of a more modern pintle-less design and
slightly flow a little more than the original injectors. I think I paid
$240 USD or so. Anyway performance is better as is Milage.

B.D.