I did the intake manifold gasket on my 98 Durango 4x4 with a 5.2 automatic transmission after doing the intake gasket I did not have spark so I replaced the computer which fixed the spark issue and it started up immediately but then immediately died I can hear what sounds like the intake sucking way too much air. when trying to feather or even gun throttle rpms raise appropriately but ends up dieing quicker. I looked for vacuum line I may have missed but haven't found anything unless I'm missing one. has good fuel pressure. have replaced map sensor TPS and idle air control none of which make any difference whatsoever. I have found conflicting reports about used PCMs. i got the pcm in it now from salvage yard. so not sure if that would be the issue there is a difference in the part numbers the original part number being 56046-364AF the used part number being 56046-364AE could this somehow be an issue any advice Direction and help would be appreciated thank you

 

There should be diagrams in the FSMs (pdfs of them are linked in the diy/faq thread) that show all the vacuum lines. If you think you're hearing a vacuum leak, start there before you spend more money. I also find it hard to believe that the computer went bad while you were working on the intake, so you might have something else going on too.

 

I've looked at diagram under hood as far as i can tell vacuum lines are ok. i know seems crazy to think pcm went out while working on intake but when i went to fire it up didn't have spark so did ignition coil still no spark switched pcm spark and fired right up like i said I've read that it can be part of the pcm security settings that will kill it Right after it starts but i am personally not very familiar with all the functions of the pcm sense it can very so much from year to year and different models and all that.thank you for the input

 

ok i went to another salvage yard for another pcm they didn't have one that had exactly the same part number but i figured id check vin make sure didn't have security system and try anyway. plugged her in and bam starts and idles no problem sounds good. as it warmed up started to have stumble issue but that im sure is vacuum line but witb a good pcm i can actually let idle and take care of tracking that sucker down. so if anyone has similar issues don't dissmiss the pcm if ive learned anything from my experience as well as the experiences of many others that i read about pcm issues can be a pain especially with all the conflicting information. yes you can plug and go with a used one. but as far as I can tell there isn't a perfect method of matching the right one but it can be done. i will track down vacuum leak now and post to conform all is well. even though i didn't get any real advice i learned a lot from other threads and hopefully this will help someone else. if they like reading long post of course lol

 

seems like everything is wrong with this truck right now. after new pcm starts and idles great but once warm it will start to stall for a second when hitting the gas. no oil pressure and temperature not going up. i think the oil pressure is because of sludge there was plenty of it in there when doing head and intake gasket so that's not to surprising. will flush her and go from there but the temperature i don't understand. i also have checked the vacuum lines so many times at this point I'm going a little crazy are there any other logical reason for starting to run crappy after running for a while? any would still be appreciated.

 

Could be something expanding and leaking (rubber hoses, intake manifold). As for the oil pressure, hook up some kind of mechanical gauge to check things. If you do still have a vacuum leak I'm not surprised that it isn't running well.

 

oil pressure turned out to be just what I thought. i flushed engine and did oil change and have good pressure back. I have continued to think there was a vacuum leak but can't find one sprayed 2 cans worth of starting fluid to no avail. all lines i check have good suction. i did drop IAC when i was putting it in. can something that miner hurt it? runs fine until warm then gas bad hesitation when hut gas. also idle will hang high when revved.
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the IAC controls the idle, if it was a big enough drop it is always possible you damaged some of the little gears in it and its not doing its thing correctly, but it usually causes a hard or no start condition when it goes bad

 

thank you didn't know that about starting with the IAC. it is pain to start when warm along with the other issues have to give it gas then feather gas to keep rpms up for a minute or it'll die again. I've read about o2 sensors causing somewhat similar symptoms is that possible or a stretch?

 

when you first start the truck it should be in open loop, meaning its not using the O2 sensors until everything is settled down and warmed up.