Hello, I am having a strange issue with my 1994 Chevy Silverado. It has 187,000 miles, with a stock 5.7L 350. For some reason when its idling it “lopes”. It reminds me of a hot rod engine with a big cam. LoL. Anyways, it runs great when your driving it. It has a ton of power and will roast the tires if you want it too. In the past 3 months I have rebuilt the engine because it was burning oil and leaking oil all around the intake, it also leaked antifreeze around the intake. So the block and heads were rebuilt by a local machine shope, with new valve guides, seals, piston rings, bearings, timing set, new cam, etc.. I got the engine back and dropped it back in the truck. After installing all the electrical components, I fired her up and she ran like woman wearing lead boots. So I began troubleshooting and ended up replacing the following parts. Throttle Body rebuild kit from autozone, EGR valve, MAP sensor, Distributor, Cap/rotor, IAC valve, Throttle Position Sensor, Coolant temp, Coolant sender, Knock sensor, Vacuum lines, Ignition Coil, Plugs/wires, O2 sensor Sense replacing all these parts, the truck runs great, and has tons of power, but it has this funky loping at idle. Another strange thing is that when the A/C is turned on it idles great. Any help or suggestions would be greatly appreciated on how to get this idle down to normal. ---------- Post added at 10:25 PM ---------- Previous post was at 10:23 PM ---------- Well tonight I cleaned all the grounds.. I got a wire brush and cleaned the connection to the block, and to battery, I also cleaned the connections to the frame and block/firewall. Still has this loping/surging and if I dont give it gas it dies.. After it warms up it will stay running, but still has this loping/surging thing. I am wondering if the computer is acting stupid. It gives me Check Engine light codes for parts that are brand new. Doesnt make sense. I checked the wiring to these new parts and its in perfect condition. Also the BRAKE indicator light on the dash is flashing. Can someone please give me some advice on what to check out next?