help! please.

lrazor said
The ammeter's antics could be due to the erratic idle.

very true

E.G.R. valve

Exhaust
Gas
Recirculation
valve

it permits a small amount of exhaust to enter the combustion chamber lowering combustion temperature in order to minimize the formation of NOx
when the valve gets old and dirty it may not shut all the way causing rough idle and stalling