Chevrolet Repair: Acceleration Lag/Timing Issue?, chain pulley, initial acceleration

Question
I have a 84 Silverado w/a small block 5.7. When I press down on the gas there seems to be a lag or bogness upon initial acceleration. Once the truck is moving above 15 or 20 mphs it stays consistent and seems to be accurate with my foot. Its the initial take off that seems strange. Also, I beleive I may have atiming issue, possibly chain, pulley?(and yes the distributor has been adjusted multiple times)  I just got a new exhaust and now when in idle, you can hear a slight skip in the tone of the exhaust, almost like the engine is holding its breath for a brief two seconds and than its constant again for a minute than it repeats.. It has never done this before and I am puzzled. Any advice would be much appreciatted!

Answer
HI RYAN, I WILL ASSUME THIS HAS A 4 BARREL CARBURETOR, [ROCHESTER QUADRAJET] NOT FUEL INJ ???? I WILL ADDRSS A CARBURETOR ISSUE. THE LAG OR[HESITATION] YOU HAVE WHEN STARTING OUT IS A ACCELERATOR PUMP ISSUE INSIDE THE CARB,THE PUMP WEARS OUT AND FUEL LEAKS PAST IT FROM THE FLOAT BOWL AREA..THIS IS COMMON OR THE FLOAT LEVEL IS TO LOW, BUT IF IT WERE THAT, IT WILL HESITATE AROUND CORNERS AS WELL,WHICH YOU DID NOT SAY IT DID. SO YOU WILL NEED TO REMOVE THE CARBURETOR AND GET A REBUILD KIT FOR IT. YOU WILL NEED THE NUMBER FROM THE SIDE OF THE CARB ITSELF TO ORDER THE KIT. THIS NUMBER IS ON THE DRIVERS SIDE, IT RUNS VERTICAL NEXT TO THE BACK 2 BARRELS OF THE BASE ITSELF[CALLED SECONDARY SIDE .. IF THIS IS A 2 BARREL CARB WHICH I DONT THINK IT IS,THE NUMBER IS ON A METAL TAG ON THE FRONT SIDE OF THE CARB HELD ON BY A SCREW. IF YOU HAVE NEVER REBUILT A CARBURETOR I WOULD SUGGEST TAKING TO A SHOP AND HAVE THEM REBUILT IT FOR YOU...WHEN YOU GET IT BACK ON THE TRUCK THERE WILL BE 2 IDLE MIXTURE SCREWS IN THE LOWER FRONT SIDE OF THE CARB THAT YOU WILL NEED TO ADJUST... WITH THE ENG RUNNING AND WARMED UP TURN 1 SCREW IN UNTILL THE ENG SLOWS DOWN, THEN TURN IT BACK OUT UNTILL THE ENG RPM'S ARE AT ITS PEAK. STOP THERE. REPEAT THE ABOVE WITH THE OTHER SCREW. IT DOES NOT MATTER WHICH SCREW YOU DO FIRST..AS FOR THE SLIGHT SKIP AT IDLE, THIS COULD ALL BE FROM A CARBURETOR ISSUE. TO CK A WORN TIMING CHAIN PUT A TIMING LIGHT ON THE CRANK SHAFT PULLEY AND SEE IF THE MARK IS BOUNCING UP AND DOWN,IF SO THE TIMING CHAIN MAYBE STRETCED. BUT LETS ADDRESS THE CARB ISSUE FIRST. GET BACK TO ME AFTER THAT. HOPE THIS HELPS TOM...