Proper testing before throwing paqrts at it.
Codes do not say replace parts but to check it out.
What did you do to get it running?
What all was it doing before you worked on it?
On the PCM change was it a used one and did you keep/swap your old prom?
Have you checked and set base timing by disconnecting the timing wire?
Has you checked the TBI base gasket?
Vacume leaks and engine missing?
Have you cleared codes?
What code comes back first?
If codes keep coming back get a good repair manual or the all data online sub and go threw the repair flow charts for the codes.
http://www.alldata.com/products/diy/index.html