1989 Chevy Silverado ping and tick noise

To whoever it may concern, I own a 1989 chevrolet silverado with a 350. I am currently experiencing a problem that I have never encountered before and have no clue as to what it is, but it definetly does not sound healthy. I recently installed a brand new engine due to a blown connecting rod and my transmission shifts perfect. The exhaust is brand new along with new exhaust manifolds. The check engine light is NOT on but the brake light is. Now the problem is my truck sounds perfect at idle with no weird sounds of any kind. But when you put it in gear and accelerate, more so when you are traveling slow, it makes an odd pinging or ticking sound whatever you want to call it and sounds very unpleasant. It is also very "deep" sounding while it ticks and pings and when you decellerate without the brakes on, it sounds like its going to stall and then leaps forward, almost sounds like it has a lopy camshaft, but normal at idle! It sounds like a misfire or advanced timing but my check engine light is not coming on so there is no way to properly diagnose it! I have installed brand new distributor components, plug wires, plugs, gas tank, and fuel lines. The fuel that was in my old tank was sifened out into the new one which had additives in it but was still 87 octane. Checked spark plugs all have a orange tint while others are a little more tinted with some white spots, but all in all they look normal no cracks or carbon deposits. Any help would be terrific and very much appreciated! Thanks!