tannerezell077
OBS Enthusiast
I have a 94 chevy k1500 with the 350 tbi. I recently upgraded from the stock manifolds to long tube headers and true dual straight pipe exhaust. The day before i got the exhaust done my heater wouldn't blow hot air anymore it was just cold. Turns out it was low on coolant so I filled up the coolant and it still didn't fix the heat, i bought a new thermostat and still didn't fix the heat. My truck has a smooth idle in park but when i put it in gear it misses some and struggles to run. it runs terrible from around 1,500 rpm to about 3,000 it sputters and won't pull a hill good at all. Its terrible on gas and sucks to drive now. the spark plug wires are on correct and i even unplugged the battery for a while to see if that would reset anything but no luck. Could it be a bad o2 sensor or maybe bad engine coolant sensor?