Rev limiter?

[qws2000]

Hey guys my car revs till max rpm 5600... When it gets to around 5k rpm it starts to breaks up... till you shift up to the next gear.. I have just changed the plugs, coil.. The motor feels like it wants to climb rite past this... Im at a loss

 

[bad V6]

Which plugs, and gap are they set at? How much boost are you running?

 

[qws2000]

ac delco .025 gap, and the boost is around 22-25psi.... any help would be appreciated

 

[TurboBuRick]

Beehives valve springs are notorious for this.