it misfires on a cold start idling sometimes. lately it misfires at w.o.t around 5k rpms. i replaced the plugs with stock acdelo's i gapped em to .032 and its still doin it. i had some lean codes while i had a catless dp so i put on the stock pipe n have no codes now. what you guys think it could b

 

my vacuum at idle is -12 also

 

ok guys i finally got some codes!!!!! only took a month of it getting worse, but code is a p2177 bank 1 lean off idle and p2187 bank 1 lean at idle
my scanners pretty crappy but the freeze frame data says my stft is 29.7 and ltft is 37.5 any help would be excellent the shop i brought it to didnt feel like checking it out and told me to try buying some ignition coils -_- lol

 

Sounds like you need to replace your WB 02 sensor.

 

thats exactly what it is actually haha i decided to just unplug it this morning since my fuel trims were so messed up and its running great now! ordered a new one today. thanks for responding, i was loosing hope anyone would try n help me lol

 

I've gone through three downstream o2 sensors im the past 5 years lol. Doesn't help it pops a flame out the tail pipe after w.o.t. shifts. I've Been meaning to get it dyno tuned but out was my daily and everytime I got money together something broke

 

im assuming u mean upstream haha its the only time its gone bad in the 40k miles ive put on the car. its weird that it can run so poorly but doesnt throw codes for the sensor

 

Never thrown a code for the upstream o2. It's always been the downstream. Probably because I'm catless