Hi. I'll make it short. 3.4 V6. 2004 grand am

Car stalls in REVERSE only and ONLY when its fully warmed, worse under load (AC on). Will jerk, sputter, rpm gauge goes crazy, chugs, backfires and dies.

Driving fwd is fine. just threw P0304 cylinder 4 misfire which might be from lifters? (i think this is unrelated to the reverse stalling) Previous owner was obviously dishonest and I got suckered. Buyers remorse.


new plugs, wires, coils, EGR valve, just changed oil and added marvel mystery oil maybe to help the lifters.

I need some guidance please.

i think your problems are related, sounds like a vacuum leak, maybe from intake manifold gaskets. as your engines rpm declines the alt output goes way down and causes that other junk. i would see about the misfire then if it is separate go from there. you have any white stuff in the oil, or rad cap? sometimes you can check for vacuum leak by spraying around stuff (cyl 4 area especially in your case) with carb or maf cleaner, listen for engine to change pitch. that engine has known issues with the gaskets and i think felpro has a updated set for the job.

Oil not milky and no signs if external antifreeze leaking. The missfire seems intermittant one second its misfiring and less power and another minute its running fine. Driving car today and its not stalling in reverse today. I cleaned the battery terminals with baking soda and the ground from battery to body. Not sure if the stalling was related to that. I found the evap hose that goes to the purge solenoid broke and I glued that back in temp fix.

that would be a vacuum leak, i dont know about the 3400 but the 3800 the hose from the tb to the purge valve goes to the fuel pressure regulator so a leak would cause the fuel pressure to be screwy too. misfires can be fuel related.

this is what was broke, notice the red silicone on it. I think its the evap purge solenoid.

Ya that side has to go toward the tb if it leaks that'* a vacuum leak

on the 3400, pcv valve goes to this purge solenoid and from there the evap hose goes to I;m assuming canister. It also has a plug. doesn't seem to go to the throttle body at all.

its got to. it might share a hose with the pcv but its job is to take the vapors from the canister and control there release into the engine. its possible that it could go to the manifold somewhere, same difference really

UPDATE: after fixing that evap purge solenoid and zip tieing the tranny wires properly and cleaning the battery terminals, it stopped the stalling. Not sure what fixed it.

Thanks also for your help guys. Greatly appreciated. Keep up the good work and may God bless you all.