I recently bought a low miles 1995 GTS. Car seems to run fine. I encounter a idle surge once in a while, but figured its due to the cam. Other than that, makes good power and doesn't seem to have any issues. However there is definitely a leak of some sort under the hood. I can't tell if its a exhaust leak or intake, or vacuum (sorry not overly car savy) but it sounds like a grinding noise very similar to this (https://www.youtube.com/watch?v=HD_BxkcUPYw). Issue was present when I bought the car, and still had the stock H-pipe on it. List of mods done by the original owner some 18-20yrs ago Edelbrock intake & heads E303 cam BBK 65mm tb Ford Motorsport shorty headers Now, the original owner is not the guy I bought the car from. Someone bought it from him, and tried flipping it for a profit apparently. Guess he succeeded cause I now own it. Anyway, I ended up putting on a used O/R H pipe. The air tube on it was welded shut. So I couldn't use EGR tube from the smog pump, nor would I since no catalytics now. So I removed the pipe assembly and just capped it off at the Air Diverter Valve. I still have that noise. Any clue what that may be? Could it be a bad seal on the EGR itself? One thing to note, I am getting rotten mileage on the car. It only has 56k miles. But I'm getting like 10mpg with my setup. It does have 3:27 gears and recently bought a SCT chip with a bama tune. Have a sneaking suspicion that EGR, while connected isn't working. I still have the smog pump installed but its not connected to anything. When the car was purchased, there were some spare parts in the trunk. In it I discovered a BBK CAI. Thought that was odd, but decided to install it. During so, I uncovered a 4-line vacuum harness (Red/Green/Tan & White) laying under the stock air box, not connected to anything. Looking at the smog pump again, I was able to see that there were two solenoids not connected to anything. I've been able to determine that the White goes to the Air Diverter Valve and the Tan goes to the Air Bypass Valve. I have connected both of those shown in the pictures Now, I am left with these Red/Green lines From what I can understand the Red goes to the back of the intake vacuum and the Green should go to the EGR. But when I look at it, there are lines already attached there. No clue what they are doing. But by leaving the Red/Green disconnected, is this possible causing any of my noises? Or bad mileage? Or should I just cap them off and call it a day?