Q: I have misfires in cylinder 7, replace spark plugs, trucks idles rough. 1997 Chevrolet Tahoe

Hello - check first for problem codes, whether your Check Engine light is on or not. Most auto parts stores will do this for free on a "time-available" basis. If the misfire is still ignition-related, check plug wires, especially the plug boots for evidence of oil-contamination and shorting of the plug wires. If the misfire is largely gone, and it simply runs rough, a dirty throttle body, or idle air control valve could be the problem. I recommend a rough running inspection performed by a mobile, professional mechanic, such as one from YourMechanic, who will come to your location, diagnose this problem, and give you an accurate assessment of damage and cost estimate for repairs.