[dgmark]

A shorted tach can be a problem, But way down the list. If it was my car this is how I would solve it

A Check Compression, Is the engine Mechanically Ok
B Check Fuel Pressure
C Put a Timing Light on the coil wire, run the engine, If you get a steady light that increases with RPM with no drop outs the primary ignition and crank sensor are most likely OK
D. put a node lite on the injectors one at a time, Is the lite blinking steadily?

Most likely with those 4 tests you will narrow down the problem to fuel, Ignition or mechanical. If you don't have the tools you should take it to a qualified mechanic anyway.