!HELP! SHE WON'T IDLE

Hey Everyone, my Girl won't idle, she's been in to my mechanic multiple times now and still stutters, stalls, lags on acceleration and gets even worse MPG than normal.
I've put in a new AFM, TPS, Plugs & Wires, Fuel Pump, The list goes on. (VERY WELL) Rebuilt 3VZ W/3K miles.
This is a real head scratcher ...ANY OF YOU FINE FOLKS HAVE ANY CLUES? It'd be much appreciated.

Regards

 

Having the same issues with my son’s truck. He’s tried a few different things which haven’t worked so I’m hoping someone here has some insight!

 

Update;

Got her to idle - worn idle adjustment screw o-ring - fixed that. Now the RPM'S jump when she's somewhere between 1200 and 2000, acceleration lags and jumps up rapidly.

Still scratchin the noggin

 

I recently did a valve lash adjustment and a valve cover gasket replacement. The valve lash adjustment was difficult and I found myself under pressure to reassemble everything. When I went to start the car, it would start and then die immediately. I tried to evaluate for fuel pump failure, but the fuel pump was fine, because I was ultimately able to get the car to rev to 2,000-3,000 revs, albeit very wildly. I cleared old codes and the car would throw no new codes - but still undriveable. So I took it all apart with the plan that I would go very slow and triple check everything when reassembling. I had missed connecting (or it had fallen off) one vacuum line on the firewall side of the engine. I had missed connecting one of the two water ports on the underside of the throttle body (with the result that the top of the engine was flooded). But my biggest error had to do with the plenum gasket. Not only did I find that the new gasket had ripped in two places, but I had failed to clean the underside of the plenum and a substantial part of the old (ripped) gasket remained. After removing the remains of that old gasket, I carefully connected the two hoses (water and PVC) that connect on the underside of the plenum. I also loosely fitted the ERG valve back to the passenger side of the engine. I then placed the plenum. Once I was satisfied that it would fit in properly, I lifted the driver's side just enough to clear the studs so I could slide in the plenum gasket, making sure I oriented it correctly. Then I gently dropped the plenum down on top of it. From there I methodically buttoned things up and triple checked my work. When I finished, the engine was a bit slow to start, then idled a bit high at 1,500 rpm for about 4 minutes, but then the idle dropped to normal and the engine ran fine. My ultimate conclusion was that I had a leak beyond the throttle body, which proved to be the case.