1993 Suburban very low idle in gear

I have a 93 suburban with a 5.7 auto 2 wheel drive, the fuel pump was just replaced and the egr valve for the code 32. But it still idle at around 100 rpm when in any gear and the brakes on the shop tested everything had it for 2 days and said they were stumped. It feels like it is going to almost stall when at a stop, but never does, and when you go to accelerate it hesitates. Any direction I can go in will be greatly appreciated.