ReDdls1

First off lemme apologize for what is about to be a book.lol. i just want to be thorough. i recently purchased an automatic 98 z28 with 80,000 miles. as i was driving it home the "service engine soon" light began to flash a few times and then just stayed on during which i noticed it was hesitant to accelerate (it had a slight miss and exhaust leak during the test drive). so i scan it the next day and get a p0300(random/multiple misfire) and p1400(egr). i then put brand new ngk tr55 plugs and new zzperformance wires along with blocking the egr off and a oil change. i drive it later that night when it was cool out and it runs phenomenally well with no hesitation whatsoever. i go to drive it the next day and after 15 miles or so the ses light begins to flash again before staying on(i noticed it being slightly hesitant to accelerate before the ses light came on) I go scan it again and get the p0300 code once more(and eventually the egr code), so, out of ideas on what it could be i took it to a reputable local shop to get them to look at it. they tell me that the #6 injector seal was leaking and drawing vacuum and a couple of my new plugs were yellow around the porcelain and was getting hot(also the pcm had close to 10,000 codes stored in it and most of them were p0300) they cleared the pcm and turned the ses light off and i began to drive home. it seemed to run well for 20 or so miles and shortly after passing somebody the ses light began to flash again.uggggghhh. today i sprayed carb cleaner around the #6 injector and the other injectors as well as the intake itself. the idle didnt change. im gonna go check the ses light shortly and will post an update

Slowhawk

iTrader: (12)

To shoot in the dark I'd probably say the Mass air meter is dirty or bad.. That or a major vacuum leak in the PCV system.

ReDdls1

i forgot to mention in my first post. the shop actually cleaned my maf sensor. wouldnt a faulty maf cause a ses light?

usmonaro

Been helping him with this car also. Did a bunch of reading, a lot of people say a bad front O2 sensor(s) can cause this. I think an intake pull and new gaskets are gonna be a next step.

ReDdls1

Update: I checked the ses light,(even though It had went off like it has been doing) it still has the p0300 code but it only says "random misfire" instead of "random/multiple misfire". Also I checked the fuel pressure at idle(car was warmed up) and it was 62psi. That high?