305/350 Swap

I have a '87 K10 P/U that was stock w/ 305. It now has a 350 with all parts moved from the 305. What changes are needed to be done to get it to warm up and idle correctly? It takes 5 min. for it to warm up and run properly. Does it need changes to computer, temp sensor, fuel injection, thermostat temp? Thanks.:bloated:

Are you running the 350 or 305 computor?

I was running a 305 computer, no adjustments had been made. I just replaced the computer chip the other day. I had a Hypertech from my 89' 350 and it fixed the problem, for the most part. The engine starts right away but after 10-15 sec. it starts to idle down and seems like it wants to cut off, but a quick tap of the gas brings it right back. Presto, runs fine. Could the second problem be related to the computer or maybe a vacuum leak??

sounds more like a vacuum leak. does the truck run like it is cold after it should be warmed up, if so u can guarantee a vacuum leak. i put a new computer on my plymouth and it acted like your truck. it idles irratically. i reset the computer and it solved this problem.