Would it affect the performance a lot? Also for PLFR5A-11 the recommended gap is 0.043 in. Should I use the same gap for a LFR5A-11 also? What happens if by mistake the gap is set smaller (like 0.038)?
Your auto parts supplier can tell you whether the spark plugs are interchangeable. The gap difference is insignificant. If the plugs were already installed in your engine and they have the same physical dimensions AND the engine runs ok, you might think about just running them for 50,000 miles and see what happens.