I have an 87 samurai i put a 94' 16v in last winter love it great power but it runs rich smells rich 13 mpg
I have changed the o2 sensor and fuel press reg has a K&N  2.5" with flow master no cat.    Can the ecu be making it run rich or am i missing something

You have 4 items that will make it run rich, the fuel pressure regulator
is usually not one of them, reason being is it takes 4 times the pressure
to increase the fuel flow by 2x, so minor fluctuations of 5 PSI is negligible.

You have the Mass Air Flow, the Intake Air Temp the Coolant Temp Sensor
and the O2 Sensor. First off, have you installed one of those snake oil power
modules from E-bay? If so get rid of it, now you need to check the other
sensors for correct values, all of which I do not remember, but I would go
get some wrecking yard ones to save bundles of $$$

The only other thing I can think of is if there is crud stuck in the injectors,
did you install a fuel filter with the engine swap? if not that could be your
trouble

Wild

new filter was done when i did the swap and its before the fuel pump(want a in line fuel pump that don't sound like a bee hive)
I have done nothing to the ecm how can you tell if some one has chipped it?  I had to turn the idle down after i put the motor in 1200rpms down to about 800 the screw is as low as it will go.    I will start testing tomorrow nabor has a tracker that never moves i can try some sensors off it or ecm

The "chip" is a resistor type of thing that is added to the intake air temp sensor
and it basically lies to the computer telling it the air is cold, it could also be added
to the coolant temp sensor to do the same thing, it triggers the cold enrichment
side of the programming that is in the ECM

You might also get some MAF cleaner and spray it out, don't touch anything or
stick anything into the MAF or you could break it and you will be pissed.

Make sure the MAF is installed in the right direction, it matters

Did the truck ever run normal, and not rich, or has it been rich as long
as you have had it running?

Also check the TPS, tho I don't think it affects the mixture as much as
it tells the computer when to add extra fuel like an accelerator pump does

Wild

has run rich the whole time I have had it the maf is pointing the right way i will clean it   I just want better mpg's

Also swap in a known good O2 sensor, I have seen new ones be
bad right out of the box, and it was a Bosch

The rich smell could be the lack of a CAT, and not enough back pressure,
how big is the exhaust pipe?

the exhaust is 2.5" with a restictor that necks it down to 2"  the restrictor is about 8"long    I had stock tracker size exhaust till 4 months ago then i built whats on it now

the exhaust is 2.5" with a restictor that necks it down to 2"  the restrictor is about 8"long    I had stock tracker size exhaust till 4 months ago then i built whats on it now

Probably too big with no restrictions like a cat to give proper exhaust scavenging.

Ya, a little big, tho a neck down should help, another thought is what if someone
put the wrong injectors into the engine? if all else fails you might check those for
the right part #