Started MTD made it seems mower self propelled auto choke from Menards 4-5 years ago. It ran very high idle, higher then I've ever heard. Then after 9-10 seconds went back to normal but still a rougher idle. Mowed 10-15 min then it choked out and died. Now it starts, runs for 3-4 seconds and does. Assuming carb related just looking for tips on repairing.