how to check and clean the m.a.p. sensor

 

Don't touch it. Once the car has a problem is when you start touching things.

 

You check it by looking at the output signal voltage under known operating conditions.... at idle, should see about 1.15V. With key on engine off, should read very close to 5.0V, depending on your local barometric pressure (significantly less in high altitude locations like Denver).

Do not try and clean it. Its a fairly sensitive strain gauge. There's no reason is should get dirty, it isn't exposed to anything other than clean air. More common problem is a dried and rotted seal, or a dried and cracked harness connector.