not sure if this is the right section to put it but here's the story. my mom's 02' Quest just started acting up yesterday, the car stalled out while at a redlight but it'll crank right up and the rpm's will start bouncing a little bit then stalls out again. if i drive it on the interstate going about 50-60 mph it'll keep studdering/hesitating and the more gas i give it the worst it gets but if i let off gas then it'll roll fine. i just installed new spark plugs, distributor cap and rotor today but still doing the same thing, might change the fuel filter soon. also the temperature gauge barely works now(won't even go past the first line).

what i can tell you before all this started happening is, before i did an oil change on the van last week, i used about half a bottle of seafoam through one of the vaccum hose and the other half into the crankcase. of course i did drain out the old oil as well. i also poured one bottle of fuel injector cleaner into the gas tank to try to help clean it. do you guys think these are the reason why the car is acting up or could possibly be something else?

 

Don't have much expertise on this, but my old Pathfinder (I think the Quests have the VG motors as well) did almost the same thing once. I opened up the air filter housing, and there was a lot of crap in there. Cleaned it out and it was okay afterwords. Maybe some of the stuff (seafoam) is just gummed up, not worked out? I never tried it before.

 

When you clean the throttle body you screw the throttle position sensor up, you may have to do an idle relearn

 

ok so i got it checked out and came out 3 codes, PO325-Knock Sensor Circuit Malfunction, PO325 pending code, and P1336 pending code-Crankshaft and camshaft sensors out of sync. do i need to replace the knock sensor w/ a new one and how do i align and synchronize with the crank sensor w/ the cam sensor? and what does the pending code mean?