MSD Sebring box issues or possible alternatives
 

I have a 94 miata with a sebring supercharger. The only management it has is a MSD sebring box. Which to my knowledge just varies timing with increase in boost.

The problem: The engine sometimes stumbles. for example; in 5th gear while cruising at 2100rpm. Or sometimes in 1st or 2nd gear if you just mash the gas peddle it will stumble and stutter sort of. I have also noticed that above 2.5k-4k you can step on the gas and the boost gauge will see 5psi but it doesnt seem to really go or pull hard until 5k.

Any thoughts, I tried searching but did not find anything on this. I bought new ngk iridiums to try. And a friend of mine has a fuel and timing power card that I was thinking about trying...I think this might be a better setup but am afriad that it resolution might suck!

any help would be great, Thanks!

What are you using for fuel management?

To my knowledge it does not have any fuel management, which is why I thought the power card and timing card would be a good idea. However, I have now been debating just getting the Megasquirt PnP...but always have hear medeoqure things about MS...Is the pnp pretty decent?

The early kits for the 1.8 just used a resisotr to trick the engine into adding fuel. Not sure if that's what you have or not. But it's not enough. The later kits come with a power card.