problems after intake manifold repair

alright here goes.....I just did my intake manifold gasket because of a coolant leaK. HAD A PROBLEM FIGURING OUT HOW TIGHT i should tighten my rockers ..figured that out. now that its all put back togetherit doesnt run right. i changed my "o" rings on my injectors there is no leak there. my car runs like its missing a cylinder it is either not getting fuel or not getting spark. I can drive my car but it has very little power. the car ram fine before i did this job. i went out and bought a gauge it tells me that i have errors....PO300 multiple cylinder miss fires....PO171,PO107,PO135,PO171and p1404 i dunno where to start im kinda confused..my wires and plugs are only a few months old and they were working fine, i labelled my plug wires but i used a white crayon and im not sure if i put them back in the right spot. ive got lots of spark coming through my wires.
Also there is a sound coming from around my injector.....if your looking from the front of the car the faR RIGHT ONE it sounds like a constant hissing sound. someone please gimme some advice on what the problem could be and how to fix it thank you.

RICHARD

for starters, engine size, make, model and so on is really needed. just guessing here, but assume you have a malibu as you are posting here, and you have either a 3.1, 3.4, or 3.8(if they put those in malibu's) since you have done the intake gaskets....in any case, this info is always helpful.

hissing sound is a vacuum leak most likely. u didn't mention if it was coming from front or rear, but if front, would suspect fuel pressure regulator vaccum line, or somewhere close to that area. either way, check ALL vacuum lines for leaks and repair as needed. regardless of where this is, it needs to be repaired first, then if misfire and lack of power are still present, then go from there. double check spark plug wire routing, and also, double check coil posts. if any are corroded, replace that coil pack. also, check all wiring for EGR and MAP sensor. could be you forgot to hook the EGR pipe back up and is why the lean codes, misfire code, and EGR code all at once, and this could have triggered the MAP code. this could be causing the o2 heater to work overtime and setting a code, or it could just be that it was time for the heater to die. post back what you find and/or what fixes it!

thank you i found that 2 of my spark plug wires were in the wrong spot and i fixed that. now i have horse power. i reset my computer and took it for a little drive after it was warmed up a bit. when i got back i checked my computer again and i got 2 errors. po300 and po171. now when my car is iddling it revs up and down and sometimes stalls out if i let it sit but driving around it seems to drive fine.as for the hissing sound i dont hear it too much any more there is more of a sound coming from my EGR valve. and my car is a 98 malibu 3.1 v6:biggrin: .and more tips?

maybe forgot to install gasket in pipe, or on valve itself, or valve could be stuck open. either way, still sounds like you have a vacuum leak for sure. may have just left EGR valve/pipe loose...did that once myself. check all that and let us know. jumpy idle can be an effect of vacuum leak, as well as stalling, this is where you need to look first now that the spark plug wires are sorted.