If you have a GM 3.1/3.4 from the years of 1991 t0 2002 you are at risk-period.
In a limited sense your observation is correct . Any " V " configured engine of any # of cylinders is more likely to develop an intake manifold leak than a properly designed I4-5-6 - it's inherent to the configuration . It's pretty simple to understand and it's been going since the days of the first " Vs " . This remark includes the Golden Age of the American V8s - ask any one who put their first aluminum intake manifold on their xyz V8 in a hurry , W/O a torque wrench/spec and with a cheap gasket designed for a cast iron intake manifold .
The concept ? Take three pieces of material of which at least the outer two are of metal . Hold the outer two in a common fixed position on yet another piece of expanding and contracting metal . Bolt together tightly so there is a tight seal at room temp or below . Now heat the outer two pieces very hot in 3 to 4 chambers .... so what happens to the seal between A TO B and B to C ? ( it gets worked hard , really hard ) . Of course , there is more . Next , cool or chill and repeat over and over and over again . Using aluminum for outer two pieces causes the expansion contraction forces on the one in the middle to become even greater .
In the field , what I've observed as the most commom cause of Int. Man. Gasket failure is cooling system malfunction or failure which in turn is usually caused ( but by no means exclusively so ) by a lack of proper cooling system maintenance and or procedure .
It can also be caused by outright component failure of many types , or combinations of many types and not just the obvious ones within the cooling system . Some worth mentioning ; EGR , any manifold heat system ( exhaust gas or coolant fluid based ) , certain A.I.R. SYSTEMs , PCV , poor /incorrect fuel , fuel - ignition - spark advance malfunctions , obstructed exhaust/clogged converter etc - the list is very long . Then there are the combinations which typically are engine /installation specific .
The key concept is anything that can cause the heads to run hot and to excecerbate surface temperature uneveness . You get bonus points for doing the same to the intake manifold and extra points for one head hotter than the other ( same for cylinder to cylinder ) . You can ring the bell if you can some get water or coolant on it again , preferably on just one . ( Garden hose water cold , 15 minutes after hot soak has commenced is the cherry on top . )
Al , I do not deny your experience nor do I doubt you had it but you have made no mention of any of the above and I havn't found anything to support yours or anyone elses contention of back to 1991 for a higher than normal incidence of intake manifold gasket failure much less the same specifically caused by defective gasket design . In fact I have found quite the opposite . Interestingly enough so far , head gasket problems have no mention , always a good sign .
