I got a 98 Audi A4 quatro. Had it one day. The kid didn't have the air box in so I put it in. Then I proceeded to check the spark plugs n they were all loose so I tightened them. I started the car to leave n bam it was missing then continued to get worse n worse. All the coils are good all the plugs are good all compression is good intake manifold gasket good changed temp sensor and icm car ran good then I shut the hood n bam it started missing again!!!!! WTF is going on!!!! Thanks

 

Definitely sounds like a loose electrical connection somewhere on the engine. Also check the ground straps from the engine to the body and the ground lugs from the engine wiring harness to the engine block. Loosen them and retighten them.

 

I checked all the ground n connections n haven't found any problems. I'm a mechanic but this is the first Audi/vw I have touched. Seems simple but this is crazy. Also throwing ismp in the dash or som n brake n abs light stay on. Would that effect any missing?

 

You need to pull the codes from the ECU first. SOunds like the previous owner (you used the word "kid") was a hack unless he was trying to figure out the missing issue and left the spark plugs loose and air box off. Anyway, pull the OBD codes from the ECU and post them.