Stalling problem rpm up to 3000 in 3 gear

I have 93 Chevy c1500 350 5.7 I have stalling problem
First was slow turn or stop in traffic it want to stall. I had
to step gas to keep it running. I change map sensor and
charcoal canister filter. It stop stalling for 3 weeks and
Now today it start stalling again but time when put it in 3
gears and rpm up to 3000 start up good rpm under 1000
in 1,2 gears in 3 gear want to die.