where is the MAP switch located?And how do you replace it?

I've just tried cleaning the MAF SENSOR, and after re-install,van accelerates better. However still not right. Tested wiring at the 3 wire plug to the MAF with voltage at the black wire around 9 volts &red at -5

well your on the right track. you need a pwr wire a grd wire and a 5v ref signal. if you can't do that try a sensor if cleaning helped a new one may be the answer