If the engine doesn't recover, the timing belt (if applicable) could have let go otherwise it could be a fuel delivery issue (dirty fuel filter, faulty fuel pump) or a restricted exhaust (damaged catalytic converter). If you have a check engine light illuminated, start with checking the codes.
in relationship to engine rpms a ratio of something like 3.08 would have less acceleration and lower highway rpms compared to 4.11s. the 4.11 ratio would give you better acceleration and less top speed and lower gas mileage at highway speed
mass air flow sensor
If it's a manual tranny, your clutch going bad
It appears that you may be suffering from the same problem i had a while back. Have you checked the wires to the alternator or even the plugs because the rev counter on a lot of cars runs of the alternator. Or it could be the alternator on the way out.
If you have an engine that idles at 6000 rpms, you need to have it checked - immediately. Around 750 rpms would be normal.
2-3 rpms
maybe your rpms gauge is broken.get it looked at by a professional
Well it should be going about 4000 rpms
Much quicker off the line, but the trade off is lower top speed and higher RPMs at highway speeds.
major vacuum leak?
Check the timing and check that the cable to the accelerator is adjusted correctly.
No it is not. Before it would hurt the valve train, something would have to happen at a very high RPMs. The timing chain going out will not hurt the valves are the head.