Last week I was replacing my IAC when I noticed that there was a decent amount of oil on the back of my engine. I checked the oil and it was down a quart from wen I last changed it back in March. I was thinking it could be a valve cover gasket. I don't think it is a head gasket because there isn't any oil in my coolant, which my friend said there would be if it was the head gasket. Any ideas?

you friend is right, it is not head gasket, also if it burns oil it could be valve seals. Another thing to check is the oil pressure sensor(not sure of the correct name). If you see oil leaks from valve covers then it is most likely valve cover gasket, but if it's all clean in there it could ba an oil pan leaking

Ok how do I check the sending units? My temp sensor iny me car stopped working a few weeks ago too.

intake temp sensor went out or engine coolant temp sensor? also if sending unit is the sensor type thing that shows oil pressure then i belive it's located somewhere near the oil filter, cause i remember mine was pooring oil out until i replaced it. if sending unit is something else then i have no idea. In general to check for oil leaks you should wash everything from oil real good and park the car overnight on concrete. In morning it would be much easier to find the leak. hope that helps

I don't know which one went out but my temperature gauge in my car doesnt work. The needle just stays at the top of the meter.

it could be the gauge or could be the thermostat.

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Yea i thought thats what it could be and replaced it a while ago but it didn't fix it.

if the car is runing fine then probably it's the gauge it self. Could be loose wire or gauge is dead
Edit: did you find the oil leak?