Theres an updated cam chain tensioner on 2009 up cobalts which is hydraulic not spring loaded. I put one in my 07, uses 32mm socket. It is larger diameter
Check fuel pressure. Fuel filter could b bad. Disconnect battery connections. Leave unhooked for 5 minutes, connect battery. Start car. Let idlle for 3 min. Turnoff car. Let sit for 3 min. Turn on car, drive it. It should reset everything. If still bad. Test tps. If u need new tps go to...
I brought my 2.2 to machineshop, they milled head. Compression to 10.0:1, polished ports, radiused first inch into port, then polished inaide of tb. Gasket match intake and exhaust ports. Makes a difference, but need 91octane only.