i changed the intake gasket on my 97 Z71 1500 pickup with a 350 vortec. it has been a few months and ever since it has a code set, check engine light is on. it comes up o2 sensor so i changed it and light is still on. now it wont run when its cold it will cut off(stall) when idling and skip and buck at part throttle till it warms up and then it runs fine!i marked the dist. and put it back as it came out but someone said i need to set it by voltage. :dunno: help please it runs so bad now i havent drove it in a few weeks!!