Why does my 87 Mazda truck B2200 die when put into gear?

Where to start is the big?One are your tune items such as plugs,wires,cap/rotor button and oxygen sensor is good condition(not high miles or age).Now I suggest removing the egr valve mounted directly under the carburetor and clean it thoroughly.Use carb cleaner and a brush or sand paper.It has one vacumm line,and one electrical connection.Now the next issue is the exhuast collector which bolts to the end of the exhaust manifold and is about the size of half gallon paint can and it has screens inside of it to catch carbon buildup and maybe clogged.To remove it requires removing the exhaust manifold and unbolt the exhuast pipe underneath due to it has to be removed from the bottom due to it's size.To clean use a new paint can(Home Depot,lowes) sell these and use some muratic acid to soak it in .Use gloves to to THIS this is corrosive.Let sit for awhile and then use baking soda and clean water to clean and neutralize the acid and blow out with air or let air dry overnite.Brake cleaner will work but, much slower process and not as effective.Now if after doing the basic stuff listed the only other item is the catalytic convertor is clogged up and needs to be replaced.This definitely will choke the engine and make it cutoff when the vehicles idle or pressure to move increase.Start with the simple stuff but,bet the convertor is the problem however suggest cleaning the egr,and tune up items and clean the carburetor and lube the linkage on it with liquid wrench especially the choke.And note if you remove the exhaust manifold soak the charge air pipe nuts,and nuts at the studs for it a day before with liquid wrench so it will remove easier and not break the studs or strip the charge air pipes threads!!