1998 Pathfinder 3.3 SE P0505 and P0100 Codes: Fix Without Throttle Body Replacement?

Hi everyone, I'm new to car mechanics and may sound ignorant — I know as little about vehicle systems as a potato! However, I've recently purchased a 1998 Pathfinder 3.3 SE and it's throwing two diagnostic trouble codes: P0505 and P0100. I’ve read several forums about these codes, but haven’t found anyone with exactly the same situation or troubleshooting steps. After cleaning the mass airflow (MAF) sensor and clearing the codes, the P0100 disappeared — but the P0505 code is still appearing. My question: Could the persistent P0505 be caused by a faulty MAF sensor? If so, can it be resolved without disassembling the throttle body? The car idles smoothly at 0.9 RPM, though it briefly fluctuates between 0.5 and 0.7 for less than 30–40 seconds after starting. Additionally, I’ve noticed a coolant leak at the top of the radiator. This raises concerns — could this have damaged the Idle Air Control Valve (IACV), or even the Engine Control Module (ECM)? If so, would replacing just the IACV and ECM be necessary? That seems expensive and time-consuming — especially for someone on a tight budget. Could there be a simpler fix that avoids full throttle body disassembly? Any clear, step-by-step advice or explanations would be greatly appreciated. I’m not asking for expert-level knowledge — just something understandable for a beginner. Thanks in advance! P.S. The vehicle is a 1998 Pathfinder 3.3 SE with P0505 and P0100 codes, and I'm looking for affordable, DIY-friendly solutions.