Your check engien light is indicating a problem with the throttle position sensor, which does what its name suggests, measures the postion of the throtle being how much you are opening it by pushing on the gas, your computer has a map the innjects the right amoutn fo fuel for each position. usually they go bad because during some points of openiong the throttle, you get no reading from the sensor at all, to fix it you simply replace the sensor.
This is completely unrelated to the coolant system.
If you are loossing coolant, it means that its escaping the coolant system somehow. You may not alweays see it leaking since it is mostly water and vaporises quickly in a hot engine environment, in addition, it may be leaking thorough your head gasket and into your combustion chamber, exiting the car aas steam in the exaust pipes, if this were the case, you woudl see lots of white smoke in your exhaust. If its leaking in the engine bay somewhere, you will see it dripping, running or whatever, or you will see it generating steam as white smoke somehwere, try letting yoru engine idle and get to hot temps whiel looking for steam to apear somewhere indicating its dripping onto something hot.
Both the upper, and lower radiator hose connections are easily seen, and access on this car to check for leaks. The upper radiator hose plugs into the thermostat housing directly to the left of the exhaust manifold (covered by the large metal plate that says "hot", and the other one goes to an inlet houseing that is visible on the drivers side of the engine.
