what can cause pinking in an engine below 3000rpm?

Are you using high Octane gas? The 4A-GE engine has fairly high compression and needs premium gas.

If it's not that, then get the timing checked etc.

Pinking??!! You must mean PINGING!

It's an ignition timing - octane problem.

Your ignition may be set too far advanced and the computer can't retard it enough.

Or your detonation-knock sensor may be defective or disconnected.

Just from what you say, your engine has too much timing.

Sometimes sloppy wrist pins make a noise like this, but it's not common.

Normally caused by timing being too far advanced. It's a long time since I worked on the Mk1 MR2, so I can't remember if it's adjustable on the distributor. It could possibly be your plug gaps though unlikely.

Fuel grade too low. Combustion chambers full of carbon. EGR valve congested with carbon. Ignition timing too advanced.

The pinging is called pre ignition. Have the timing checked or use the next higher octane gas.

The word is pinging. It usually means the octane in the gasoline is too low.

THE NOISE IS A PING AND BOTH IGNITION TIMING AND AIR FUEL MIX CAL LEAD TO THAT.

Something wrong with the knock sensor or the electronic spark retard system.

you need to check your timing ..its too advanced