I installed the viper coil pack and 4port fuel injectors from kuspension and new spark plugs and now it sputters. I switched back to stock injectors and problem slightly improved but still noticable sputter. They are sending a new coil pack to try. What do you think is the cause? Could it be plugs or wires that came with coil pack? It's a 2001 with 93000 and ran perfect before was hoping to get better fuel mileage as I seen on web

 

In my opionion the k suspension stuff is just cheep parts hes sourced yes yes it could very well be the new parts.

 

While I wouldn't want to have to do this suggested he put in the old injectors and see what happens.
But thinking about it more now probably better to throw the coil rail back on first.
Figure it is the easiest thing despite me thinking more a fuel issue then a spark issue.
I did the 4 hole injector upgrade years ago.
Bought brand new ones from a company local to me. Cost me $300 back then.
And when I say local I mean 15 minutes away.
Always been a little embarrassed by that seeing how guys were getting good results with boneyard swaps and whatnot.
Don't regret doing it and over the years reading about guys having problems here and there am not quite so embarrassed about it today.
I don't think there was really any improvement in MPG but the butt dyno did say she seemed a little peppier and idled a little smoother.
Somebody a long time ago posted that any improvement you do see from the 4 hole injector upgrade is not because they are 4 hole ones.
Just the simple fact that you have clean injectors in there that don't have 200K on them.
Always kinda agreed with that.
LOL.

 

I put old injectors back in and it made a slight difference. So I'm guessing it's the coil pack or plugs I put in not firing right.