Thanks for the reply mechy1barry,
No hoses going to the oil filler cap, it is just a screw-type cap on top the valve cover (camshaft cover?). It's an overhead cam engine.
We have tried a different MAF sensor from another car and can't hear any vacuum leaks, but that's not saying that there couldn't be any. Not sure of the best way to check for vac leaks. I used my hand vac pump on each vacuum line going to the vac distributor with the car off and the ones that should hold vacuum do (checked them against my good Escort). Don't know how to check for a vac leak around the MAF sensor.
Thanks again.