Engine Surging and Stalling

[mrgmguy]

Ok so i got a 2000 buick century that had blew the lower intake gasket. i had put it off for about 2 months as i was moving to a bigger house tools were packed ect and i wanted to wait till i go to my new place.
Anyways i decided to pull the heads off and change the headgkets aswell incase as the car only had 130km on the engine i figured if i did all the gaskets id get a couple more years out of it as a winter car.

so heres my problem once i got the heads off and everything cleaned and ready to be put back on it took me almost 3 months to get the right gasket kit and new headbolts.

I torqued all bolts to gm specs
Pushrods were kept in order

when i start the car now with everything back together it surges real bad sometimes shuts off pulling codes p0300 engine light flashes, engine smooths out for about 20 sec at some points then goes back to surging. when it dies it sounds like its knocking out
I even went as far as resembling the intake again to re-check the pushrod order and its correct.
the car only had less than a qaurter tank of gas in it when i parked it aswell the gas cap for the car was off for the 3 months dont ask me why lol.
COULD IT JUST BE BAD GAS ?????????????

thanks for any help

Topic

[John B Kobberstad]

Is this a 4 cyl engine?

[mrgmguy]

V6 3.1L sorry

[aknight_sa]

P0300 is the random misfire code, which means you could be having misfires in several cylinders. misfires could be due to loss of compression, ignition or fuel injectors..

for what you described the cause could be the first as you just changed the head gaskets which could mean something went wrong when you were bolting it..

but also, the no gas cap for three months could have got water in the tank.. so i would start by flushing the gas tank first then refilling it with new gas, then carry on with tests..

[EricTheCarGuy]

If you have issues after doing work like that it’s always good to go back and recheck your work to make sure everything is connected correctly especially after that amount of time. Vacuum leaks are the first thing that come to mind so you might want to check for those.

[Author]

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