Engine swap help

I just pulled a very good working 305 TBI out of a 1988 Chev truck 2WD, and
put it into a 1987 Chev Silverado 2WD. After hooking everything back up on
the Silverado, the truck fired up right away. It ran great, up until it got
to operating temp. When I try to drive it, it starts to backfire through the
throttle body, and quits. When I try to restart it it rolls very hard, just
like the timing is off. When the engine cools down, it fires right up and
runs great again until it reaches operating temp. I know that the
Distributor never moved during installation, so I can't see that the timing
would be off. Would the computer from the 1988 truck be different than the
1987 Silverado? Or something else. Any suggestions would be greatly
appreciated. Thanks.

Mike

I put a tester on the truck, and I am getting a code 42. Would anyone know
what to look for on this code warning?

Thanks
Mike


"Craven12" <craven12 DeleteThis @personainternet.com> wrote in message
news:10pfusem98ltt4b@corp.supernews.com...
 >I just pulled a very good working 305 TBI out of a 1988 Chev truck 2WD, and
 >put it into a 1987 Chev Silverado 2WD. After hooking everything back up on
 >the Silverado, the truck fired up right away. It ran great, up until it got
 >to operating temp. When I try to drive it, it starts to backfire through
 >the throttle body, and quits. When I try to restart it it rolls very hard,
 >just like the timing is off. When the engine cools down, it fires right up
 >and runs great again until it reaches operating temp. I know that the
 >Distributor never moved during installation, so I can't see that the timing
 >would be off. Would the computer from the 1988 truck be different than the
 >1987 Silverado? Or something else. Any suggestions would be greatly
 >appreciated. Thanks.
 >
 > Mike
 ><!-- ~MESSAGE_AFTER~ -->