After swaooing my 305 to a 350 my engine seems to idol high. At almost 900 RPM. (That is after its up to operating temp) Besides that. I set the timimg at 900 during idol and it runs great. After then engine is cool (of course i reconnect the tan wire) and i go to take it for a ride and press the brake and shift it into gear, and wile my foot is still on the brake the engine lowers itself to about 700RPM and the engine struggles to stay running. Does anybody thing that maybe the timing could be fine at a higher rpm but when i put it in gear the timing is far enough off that it can barely run?

 

Do you have carb (computer controlled, I assume), TBI, or TPI?

 

Did you put a bigger cam without adding a stall? My friends truck drops to 500rpms (stock tach is probly off but it is still low) when you put it in gear, so as long as it still runs decent at idle in gear i wouldent wory about it.