Your question isn't specific enough. there are many reasons why an engine could run bad.
stopped up fuel filter or poor fuel delivery
It will fit but it will NOT RUN. To make that engine run you would also HAVE TO HAVE the 94 computer system, Engine wireing harness and transmission wireing harness. You will also need to remove the 97 fuel pump and install a 94 model fuel pump. Reason is that the fuel pressure required to run the 94 engine is alot less then the 97 engine requires.
NO.
no
Yes, it will.
Yes, They will bolt right up.
No
Yes they sure are.
A 195 degree should be used.
no the blocks are different sizes in that much of a time span
YES
1986-94 Chevy 350.