I just did an intake swap Weiand "Team G" sweet intake but now i have this severe stumble when its cold when its warm the car pulls hard and no ploblems I replaced the wires cap and rotor plugs where changed 400 miles ago and timing advanced to 6* with 94 octane
and when it stumbles like after school in the parking lot I'll pull out put my foot in it and it falls on it face HARD it seems like plug wires so I bought a set of Accels and put them after I pulled the intake back off to fix the rear intake seal all ways hook your PVC valve back up or learn the hard way I did
took it for a test drive pulled nice and hard no problems then this morning stumbled like a bitch
I think its ignition but really dont know where to start looking beings everything is new but the coil or could it be the coil

 

might be running lean. when u let off the gas does it gain life again?

 

No its pretty constant thing hold it to the floor in the mornings and it will stumble and carry on like its missing a few cylinders but driving off the line it falls on it face hard then picks back up till 3000 or so then it acts up and only at full throttle
I changed the plugs today they didnt look right #1 plug had a yellow tint to it eletrod porsolen and all then the rest looked burnt on the porsolen only in a small spot and the eletrod looked unused dont know I had it pinging pretty good when I bumped the timing to 6* and had 89 octance now I have 94 and no problems well other then wedgeing my self out of my seat:lala: it pulls hard with this new intake now I need to finsh my heads and get headers

 

Sounds like a possible vacuum leak somewhere to the throttle body. Did you 86 any of your vacuum lines in the process of upgrading the intake? Somethings telling the computer to send the wrong amount of fuel while you're still in open loop... probably one of your sensors not hooked up.

 

Dex......What exact manifold is that? Part number?

 

weiand #7525 its also $183 from summit I bought it used:lala:
No I have all my vacum lines had to tie into on so i could have power brakes just got a little 3 way adapter I dont remeber where it orginally went to. It is a little fitting that is on the pass side behind the TB and theres not a lot of seners either. There is one on the front of the intake coolant temp i think then 2 for you TB and one for EGR which i dont have hooked up and it hasnt given me a check engine light either

 

did you remove the thermac? mine does the same thing when its cold , no biggie

 

Maybe you should think about having you're coolant sensor replaced.

 

FWIW, I had the same problem after modding my engine. The manifold is still stock but I made a 1/2" thick TBI spacer that eliminated the problem. I'm not positive why but I'm guessing that the mixture velocity was increased to the point most of it hit the bottom of the manifold and the spacer added enough length so that the fuel mixture had enough room to make the bend into the manifold runners. Only had problem when cold, after engine was warmed up the car ran fine. Whatever, it worked for me.

 

Well I found a problem vaccum leak under the PVC hose forgot to hook a vaccum hose up also found out I was a gallon low on coolant always tighten those heater hoses
if this didnt fix it I'll change the coolant senor i still have the thermac just laid it on the intake out of sight
also went to the track and ran a VERY disappointing 15.3 ran a 15.0 a week ago now i need some 350 injectors finsh my heads get some headers and I should be good to go
I also have a 350 with L03 heads, cam unknown, weiand intake, 305 injectors, no cat ,3 " exhaust all backed by a 700 R-4 and 2.73 posi