Toyota Repair: Engine Overheating, coolant leak, toyota 4runner

Question
I have a 91 Toyota 4Runner for which I have experienced the following chain of events.  I noticed a big pool of coolant under my car but when I checked the radiator it was full.  It ran fine and did not overheat.  I took it in for service and the Tech said the water pump was leaking.  I declined to replace it since the leakage had gone away and the engine was not overheating.  The engine then almost immediately following service developed a significant oil leak and I took it back to the dealer for inspection. They denied the cause was due to their service but the oil leak cleared up and now seems fine.  The engine then stopped holding rpm at idle but I did not notice overheating (it may be because I didn't look closely).  Now, I am noticing the temp gauge tipping toward red when it looses idle speed and the engine will cut out.  When I pressed on the accelerator to maintain the idle speed the gauge moved back to normal running temp.   Today, the temp ran almost to red and was not nearly so responsive to my pressing the accelerator and for the first time the temp went up when I was moving at higher rpm.
I suspect this is fuel pump but I am a little distrustful  of the dealer after my oil leak problem.  It would be great to have your opinion before I return to them.

Answer
Did they explain to you what the oil leak was and what they did to fix it since now there is no oil leak it seems irrelevant anyway, the problem is the overheating, they should pressure test the cooling system to locate an external coolant leak, if no leak is found then it's a matter of not enough coolant circulation, this could be simply a stuck thermostat or something more serious like a partially clogged radiator.