Problem with a 2001 Mazda MPV

My 2001 MPV is experiencing

“surging/hesitation” problem when runnig at 40-50 mph. The problem started whrn the ignition coil and spark plugs were replaced the spark plug cables were later replaced but the problem reappared.

We had a rash of bad plugs by a particular brand of plugs. we spent many hours trying to fix a similar problem before we checked the 8 new plugs of which 4 were bad.

brmurph00
Thanks I will look into that.