cuts out at 4,000 rpms

Just did MAF conversion

86 gt with ported e7 heads and trackheat intake

got codes

21, 41, 91 while running

O2 are new


just like breaks up kinda missin bad


timing is about 13* running 93 octane


just at a loss..


also my break pedal gets hard sometimes then i start driving again and goes back to normal!??? vacum leak in booster?


any ideas thanks!