I have a 92 mustang 5.0 with no real mods. Just a CAI. The car has a new distributor (6ish months) a BRAND new TFI (replaced a couple day’s ago) new plug wires, and a new coil. The head gasket was relatively recently replaced. For a while now (when my EGR was deleted) the rpm started bouncing. It was hesitate under load, and misfire and pop constantly. I put the old EGR on and the problem was gone for a couple days. Started again, so I cleaned the IAC. Didn’t change anything. Kept doing it, so I came to the forums, and saw the TFI is a problem. So I replaced that, and it ran great for 3 days. Now, today, it’s back to it again. I have an EGR code, and a HEGO code. Both oxygen sensors were replaced a while back. Not sure what to do... we are replacing vacuum lines currently, and I have no idea how long it’s been since the plugs have been replaced. (Not since I’ve had the 5.0 for a year) any ideas?