I have been working on this one for a while trying not to throw the wrong parts at it. I replaced the fuel pump 2 months ago and fuel pressure is now at around 38 psi goes up a little over 40 so that is good. I checked the plugs they are showing a rich situation black soot. used an ohm meter on the o2 sensor started low went up to around .8 volts fluctuates on acceleration down to around .3 so that should be good. checked for vacuum leaks by spraying soapy water on vac ports hoses and around the intake I am at a loss can anyone help? I changed the iac the surging still stops when it is unplugged.

Did you check the fuel pressure regulator?

WTF is a sand rail?

what gen engine is it? l67 spec is 45-55 psi, if you have the right pump i would say regulator or filter.

like a dune buggy

The fuel pressure is close to 44 psi when the vac line is unpluged from reg bur makes no diffrence that is why I ruled that out but maybe I should look into it some more. I am not sure about the engine as I was told it was out of an 88 acura lol.

I never knew they had 3800'*. ???

if you could post a couple pics someone should be able to help identify it, so you did or didn't do the build? curious about the computer and such

I did not build it I am looking into buying it, I was told it was a super charged acura v-6 but it is obvious to me that it is a 3800 early gen
I have not been able to locate the egr valve I am not sure it still has
one. I am not sure what year it is for sure, but I do know it is running
34 lbs fuel pressure I am not sure that this would cause the surging
or not but I have seen sevral posts calling for 44lbs minimum the pressure
goes up to 42 with no vacuum but runs about the same as far as I can
tell. checked the pcv it rattles, and checked again for vacuum leaks
would just 4lbs of fuel pressure cause this problem? I have never had a regulator go bad before do they usually drop in pressure? any input would be helpful

that seems normal if its a early one, post i read say its supposed to go to 50ish with no vacuum line. when they fail your computer isnt getting the right fueling for its duty cycle. its try to make up the engine could be varying hard to tell when something is wrong. take a sniff of the part where the line goes if you can smell gas you know for sure its bad

If the owner is claiming its a Acura V6 and your saying its a 3800, that doesn't give us much to go on. If you could post up some pics of it, that would help out immensely. No sense in us trying to diagnose something if its completely the wrong engine. See what I mean?