Fiat bravo just doesn’t work !!!!!!!!!!!!

hi people, have a fiat bravo with engine code : 182b9,000 so a 1,9 jtd with 74 KW and 101 ps. now to the problem : he just didn’t go anymore and stopped at 3000u/min at full gas, then I changed the air mass meter and the agr valve, now he went again reasonably !!!!!!!But !!!!!! he only pulls through once in a while, sometimes he has real power and then nothing goes ahead. in the first gear he pulls through properly and when I then switch into the second gear at once nothing goes through more, since he partly stops right at full gas, then gives nen jerk and he pulls again but not properly ………what the devil can this be ??????? have even changed the diesel pump in the tank……tom we’re beginning to find nothing more for tips we’d be very happy about