I bought a 1990 Bronco 2 months ago and I was thinking about doing a tune up. New plugs and wires, distributor and button, etc. I was looking through the glove box and found some receipts where the previous owner had already replaced the spark plug wires and distributor and button a year ago, but since then he had been down to the river and got mud all over the engine and never cleaned it. So my question is should I do a tune up or leave it alone since he alread replaced the plug wires and stuff a little over a year ago? Thank you for your time and advice.