I come from fox bodies, so I'm new to the 4.6. I'm wondering if my 04 has the upgraded manifold? Under load on the freeway it gets a little bit of shaking like its motor mounts, but it seems solid at idle, any ideas what it could be? Heres some photos of my manifold. Thanks
I don't believe they used plastic ones in 04 still (should have been changed by 99-00), but either way, that has the aluminum crossover, which was the main change between the older and newer ones (the old ones are fully plastic).
How many miles on the car? Any check engine lights? Automatic or manual transmission?
Shaking on the freeway when you're getting under load always makes me think coils since that's been the issue on 3 past Ford products I've had. I've recently learned you can get replacement boots and springs for them and they are often the issue rather than the coil itself. Much cheaper, too lol.
Looks like the stock 04 manifold. The 04 manifold is the best PI manifold. No reason to upgrade unless you start making major modifications.
The shake could be a number of things: bad alignment, bad tires, worn bushings, worn shock/struts, and/or worn mounts.
Make sure all the basic maintenance is performed, check your tires, get an alignment, do a bounce test, rev your engine and watch to see if the motor mounts appear worn, and then do some further diagnostics towards your problem.