Iratic tick over

Could be many things. Sometimes Exhaust flange joints will get a gap in them and tick. You could be hearing the Injectors, or hydraulic lifters.

The exhaust tick and lifter tick both are temperature sensitive as opposed to the injectors.

What you could do is run the engine and drain the oil and put in fresh cold oil. The first few seconds the cold oil will be thicker and if it is a lifter problem, the oil will cushion the noise temporarily until it warms. The exhaust will already be hot, so you will notice a noise on startup. If the noise generates later, its an oil related problem.

The exhaust flange problem can sometimes be heard when backing up and reversing direction. The Torque puts a strain on the pipe joint as the Torque changes from Reverse to Forward.

I hope my Solution is helpful.

Poor earth connections cause all sorts of nasty problems, newer vehicles have so many sensors that require earth connections and are more sensitive to resistance changes due to poor earths.

Possible Mass Air Flow sensor

SOUND LIKE YOU HAVE PROBLEMS WITH THE IDLE SPEED CONTROL.SCAN VECHICLE FOR A CODE.

check your catalytic converter, and check to see if you have oil in the water or visa versa

have your Idle Air Control motor checked by a qualified service technician.

Most likely a bad ground ! Or bad connection at the connector.

if the battery was disconnected it may need the throttle readapted with a vw scan tool or have a vacuum leak

Vacuum Leak.

Could be the IAC (Idle Air Control) valve. I had a similar problem on my old integra in the winter and that was the problem. It's on the intake manifold and for the older integras i know is kinda common.