1990 Ranger

I have a 1990 ford ranger. It just started to missfire when I come to a stop, once I let off the breaks it starts to run smooth again. this is getting worse. any ideas ? I`ve replaced the plugs & wires,and fuel filter already its is a distributerless engine with the dual sparkplugs . so its got 8 plugs for a 4 cylinder motor..

Sounds like you have a vacuum leak in the brake booster. Just for a test, remove and plug the vacuum line going to the brake booster.

But remember ... you won't have good brakes during the test!

well when I removed the vaccume line I heard pressure release so I know theres no leak, but,,,, ever since i released that pressure and put the vacumme line back it seems to have cured the problem... I hate it when I fix something and I dont know what I did.. Thanks for the help..

I hate it when I don't know what I did ... and don't fix something.