free advice on the 83-87 telstar

[dirty hands]

already been to two mechanics and they dont know - great

if its a carby the fault will be there or spark from the coil to the plugs
notwhere else it can be

recheck timing and for cracks in dissy cap

clogged catalytic converter-- yes if the engine has been burning a lot of oil - you can take the system apart and check to see if its clogged badly

go to the tail pipe and see how much pressure is comming out the back should be eneough to move your relaxed fingers