I have an '89 305 TBI with 160,000 miles. It puffs out blue smoke for a second or two when you start it after it's been sitting a while. This seems to be pretty common on these cars from what I've heard, so my question is: Is it the valve seals, the guides, both?? or could it be the rings already? the car is in great shape and was very well taken care of by the one owner that had it before me so...plus I never need to add any oil between changes.

Also, the engine seems to run a little rough (dash pieces and stuff rattle quite a bit) at between 1200 and 1500 rpm--especially when cold, but at normal idle (750-850rpm) you can't even tell it's running. Could it all be related?

Thanks for your input

 

Sounds like you probably have bad valve seals. Since your are having this problem the rough idle could be caused by fouled spark plugs!!

 

I hope that's the case. The seals are a lot easier than the guides. I have an on the car valve seal compressor.