Ignition miss
 

Looking for a little help with my 87' lx lets start with a quick list of mods, K&N airfilter, 1.72 roller rockers, 5 angle valve job & fully ported stock heads, aftermarket 1 5/8 shorties, aftermarket dual cat H pipe with aftermarket cat back. The car runs well but is developing an intermittant engine miss, it happens when the engine is lugging, like 60mph @ 2000 rpm and i try to accelerate easy. It stumbles and miss's if I down shift and increase rpm's it seems to go away. I first noticed it after i put an MSD 6al box on the car. I sent the MSD box back to MSD, they returned it OK. Now the symtom is there (though not as bad) with out the MSD box. Any Ideas? Thanks...