Please If any buddy has any idea!! My 6.2 diesel won't go over 30/40 mph could it be a cheap 20$ lift pump I just replace? Or maybe my injector pump? Can I test it? Just last week it went for a 400 mile trip because it was running fine again but now nothing over 30/40 mph.
It's confusing me on what it could be.

 

well if you have electric LP just put 12v right to it see if it pumping fuel also you my want change out fuel filter maybe so water in the fuel

 

I would guess fuel filter.

 

Just Replace Fuel filters and mechanical fuel pump/lift pump.
also an electric booster pump, so wouldn't I have enough fuel?

 

Dose it surge at 35mph or does it just level out?

 

It just levels out, I can floor it but nothing happens and it sounds like a gasser (no clatter like a diesel)

 

To me it sounds like you are not getting fuel to the ip. I know that is pretty open but it could be a clogged filter, clogged line, or bad lift pump.

 

I know this all started when i replace the fuel filters a few weeks ago, maybe could I have done something wrong?

 

That could be a possibility maybe when you took them off a piece of junk got into one of them or in the line. I would pull the filters back off and make sure the line to the ip is clear.

 

Good Idea I'll do that tomorrow.