i have a stock 4.3 in my s10 blazer right now... and everytime i turn it on it runs real real ruff. smells like it is flooding itself. give it about 2 minutes and something kicks on and it runs fine. it will run good for a few hours and then start running ruff again and some times stall out as i come up to a red light. i have changed the air filter, oil filter, fuel filter, cap and rotor, spark plugs and wires. any ideas on what could be wrong with it.