2005 Maxima SE
I've now been to two dealerships and 4 local mechanic shops. Nobody has a clue. Just keeps telling me different things. So some advice needed and a question for you

I noticed one of my flex pipes is a bit shreaded and could soon be a full out leak.
Is it ok to chop out the flex pipe thats shredded and just weld a new one in place like I did on my 4th gen? It looks a bit more complicated and $800+ for the entire section of piping seems a bit retarded. This isnt mine but its a picture of the section I'm talking about:

Could this cause random idle at normal operating temperatures?

When I'm parked after have been driving for 15-20 mins so at normal operating temp all of a sudden my idle just jumps to 1.5-2K for no reason. When idle at a light I'm getting rough slightly low idle and tons of vibration in the steering wheel and a dull bass like muffle sound plus when I accelerate sometimes I lose all gas pedal and the engine feels choked, cuts out, and the car either goes into limp mode or fixes itself once im going above 40 or so.
Also when I rev up then watch the revs going down the needle lags and jerks down slowly. Its not smooth at all.

I have replaced:
- front right upstream o2 sensor by the firewall,
- spark plugs,
- throttle body,
- MAF,
- air filter,
- did a tranny flush.
- All other fluids are fine except I do have a small p/s leak (it was really bad even from the pressure switch/sensor on the high pressure hose which I replaced as well which fixed the leak when it was really bad. So now maybe from the pump or other part of the hose.
- I've done 2 idle relearns at the dealership as well

Happens way more frequently when it rains!

One dealership says it could be the ground wire. Sometimes I notice some flickering in the gauge cluster lighting. Dealership did say the batt voltage was a little jumpy or something to that affect. Could this really be the cause of all my problems? Why would that really only occur once the car has warmed up fully?

I've spent nearly $3600 now trying to fix this issue. Its extremely dangerous. HELP!
NO CEL CODES.

 

Looks like you got a lemon bro

 

Sounds like your alternators taking a dump. Does your dome light lightly strobe when the cars running? Indicative of failing diodes in the alternator. And seeing as your rpm are jumping about, I'd say it's worth a shot.