Rough idle.
 

This is all when the car is cold. It starts up fine. When I shift into reverse the idle seems a little rough and the car is slow to reverse for like 20-30 seconds (rough guess) then it smooths out and it starts to back up faster. (This is all without any gas applied). It didn't use to do this but it didn't just start to happen after any particular part was replaced. I thought it might be the maf. I pulled out the old one and one diode? was broken and the plastic cap piece was stuck inside. I pulled that out and replaced the maf; however, (short version) the new sensor I had purchased ended up falling. Neither diode on it appear broke but it doesn't have the cap that goes on the top. Could my issue still be the maf? If not, other suggestions? I don't notice any roughness in the idle once the engine is hot. I was thinking if its not the maf then maybe a hose has a leak that goes away when everything expands from heat but I'm not really sure where to look.

Well for the record, I bought a 2nd maf and installed it. Cleared up my problem. So yes, that little plastic cap is necessary even if the diodes on the end are fine.