98 ck 5.0 to 5.7 swap

[rcb98chvy]

My 5.0 went out after 312,000 miles I replaced it with a 5.7 . The problem I am haveing is I dont have as much power as I did with the old motor . I havent changed the ecm program yet but I am tomorrow. GM said that they didnt have a prog. to fit my truck because they didnt make a truck with the same 4spd. auto and GU6 "342" rear gear with a 5.7 motor only the 5.0 in 98' but I found someone who is in the performance clik who can install a converted factory prog. ( I cant even power brake..lol ) I have been to 5 dealerships and paid for 3 diagnostics and no codes came up on computer over $300 and havent gotten any results! Half of them blame the old 5.0 prog. and half say it doesnt make a difference from a 5.0 to a 5.7 where the comp is concerned!! It has absolutely no lowend power and moderate mid and high end! Anyone ever been here before?!? Would appreciate any help!!

[wehswarriorS-10]

well yeah the computer would make a world of difference, if u hve a computer for a smaller engine in a larger engine, ur injectors arent sprayin all teh fuel the bigger engine needs, and a multitude of other things, get the right ecm and it should run alot better

[rcb98chvy]

Got the right ecm but it didnt really help much.. runs a lil smoother but still doesnt have any low end torq.