Digital numeric display/$20/ship same day.Equus Innova 3145 OBD-I Ford Scan Tool
In order for it to do a cylinder balance test, your engine has to be MAF/SFI. Alas, your engine is MAP/EFI. The transition year was 94'. But you need to run the Error Code scans anyway. Probably the best $20. you ever spent (except that time in Mexico!) You could have poorly atomizing injectors (Lucas injector cleaner). 302's are notorious also to miss when wires are not ran correctly. See this link for proper routing: Ford Fuel Injection » TroubleShooting EFI Problems
A can of Seafoam 2/3 through the power brake booster Vac hose, at normal op.temp. & idleing, shut off for 15 minutes, then blow out by revving till the smoke clears. The other 1/3 in the tank (Always helps idle). I also suspect maybe poor EGR flow, you need to run Error code scans to help I.D. for sure because that doesn't mean the valve itself is the problem. Buy the Code reader before you start buying a bunch of parts you don't need!