Ok well I'm new on here and have been finding good info so figured I would join.

I bought a 1999 baja outlaw with a 454 mag MPI
I've been doing nothing but fixing the previous owners hack job on just about everything!!
The boat had a steady flat spot at about 3,500 or so when I took it out before I began any work. After taking back home I started looking into the ignition parts, one plug wire was rusted full not even touching plug so I replaced the cap, rotor button, plug wires and plugs. I also added sea foam and after I added the sea foam it would nt even rev past 3,000 rpm but maybe one time out of 5 attempts so I'm assuming it knocked something lose in the fuel system?? Did I mess up the electric fuel pump? How do I remedy this problem? I'm supposd to take a trip leaving wed and boat is far from good.

Also on spark plug note someone said run the bpr6efs plug... Is that ok? I noticed the reach is over 1/4" longer than the ac delco MR43T that I pulled out...
I gapped them at .35 like a stock plug says to, is that correct?

Sea foam shouldnt do anything to the fuel pump but a plugged filter can cause problems like that. I would replace the filter, see if there is anything in the old one, if the fuel smells bad change it. wouldnt be a bad idea to check fuel pressure also, not sure but I think it should be in the 36-38 psi range & steady. As far as the plugs go if the tag says mr43t which I think it does I would use them. If the plugs stick too far into the combustion chamber they can hit a piston! Also would be a good time to do a compression test to see where your at. Hope that helps, Randy

Compression is good, I checked that already. Changed fuel filter also and wasn't much of anything. Pulled the plug and no damage from anything like plug being hit by piston. Checking fuel pressure in am.

How do you suggest going about changing 70ish gallons of fuel??

On mine i disconnected the fuel lines from the engine added some line to get it out of the boat and put air in the fuel tank with a compressor not to much,it will come out.

sounds like a clogged injector or 2....common

So how do I "unclog" the injectors

Well I changed plugs to ac delco 10 which is what they said was cross to mr43t.
And I put a gauge on schrader valve to check pressure, it's 34 at idle, fluctuates bad by 6-10 pounds, at any given rpm, when I rev (this is out of water in a bucket in neutral) it gets to about 3,000 rpm an will drop as low as 26-28 then jump up to mid 30s but it stumbles and falls and such. The thing I don't understand is the smell of raw fuel when it does this??
Please help running out of time

Checked it again with fuel reg vac disconnected, fuel pressure was right around 40-42, when you revved it the fuel pressure drops a bit then when you rev to where it's at 3,000 and stumbles bad it flat lines at about 32

I think you found your problem, pressure fluctuating like that wont fly. With your time constaints you might pull the injectors & check for contamination in the fuel rails, ohm out your injectors & replace bad ones unless you have someone local that can clean them. F/P should remain constant throughout the rpm range. An injector that is stuck open will cause f/p to drop out, raw fuel smell, & can wash down cyl walls causing more damage. Does the oil have a fuel smell to it?