recent heater core replacement. ran ruff now, cranks but no start. whassup?

What is your question?

when i picked up the car from the shop, it would hardly run. since, each day worse. dies, restart but coffs and bucks very unvolvo like. wonder if the fuel pump relay is the culprit. how do i test the relays integrity? Voltage meter? Sounds like a learning experience. btw, i checked the coil, and i'm gettin plenty of spark. H20 in the gAS? on the right trail?