Jordan Richard

Good day everyone, I'm new here. I got a 92 gmc sierra k1500 with the 5.7 L. So my truck starts fine when cold, all normal. Once it reaches operating temperature it starts to shake or cause loping. I used the ALDL connector and wasn't getting any codes other than the 1,2. I'm really not sure what could be causing this issue as since it starts and runs fine till warm I'd think the fuel pump, filter, spark plugs, throttle body should be fine. I'm sort of leaning to a vacuum issue within the EGR system possibly. The EGR valve moves with my fingers with a bit of effort but not much. Any help or suggestions would greatly appreciated. Thank you in advance.