Ok I will def check that yeah on both motors first turn of key is 10 psi if I keep turning on off it will keep rising to 25-30

sounds like you have a fuel problem.use a gas can and plumb it into the system,eliminating everything before your fuel filters.you have a new fuel filter on these motors ,,right?lets see if the pressure comes up.

Yes I have changed them

Gas fuel injectors are rated at 43psi for flow. The fuel pressure regulator is often controlled by vacuum. The less intake vaccum, the harder the engine is working and using more fuel, so the regulator increases flow to ensure adequate fuel pressure. Fuel pressure is directly related to fuel metering flow.

Low fuel pressure, means less fuel flow. If the EFI doesn't have closed loop feedback, it doesn't know its only putitng in a small amount of fuel. Bit throttle blips need a massive amount of fuel to get the engine mass moving. Just like a carb's accelerator pump shots. If you can't deliver that, the engine will fall on its face as its too lean...with no energy to rev up.

Lots of reasons for low fuel pressure. I wouldn't look at anything else as an issue until you get the pressure up.

Not to mention...the injector atomization at low pressure is poor, amd makes less of the fuel available to burn, so even though you have fuel in the cyl...its seen as even leaner.

Ok thanks for that I’ll definitely look into restrictions and the check valves

Having the wrong stat makes me think your cooling is off. Does that motor have the crappy rubber piece for water intake? You get surging and rough idling if it’s not getting water to cool.

also that fuel pressure is super low for EFI. Something else is probably going on there too.

what do you mean by crappy rubber piece and motor now has 160* stat insatalled

your thermostat and it’s the impeller of your water pump.

Ah I haven’t pulled the water pump off to see

the fuel regulator are 1:1, have a hose to de intake for referense?... At idle or partthrottle there is a lot of vacuum in the manifold and the regulator causes the fuel pressure to drop to maintain a constant flow.