Buick Lesabre Hard start after sitting Always!

Hi I have a 1994 Buick Lesabre custom with a 3800 engine in it. I have owned it for one year and at time of purchase the engine light was on, it was at a great price and it drove good. So we purchased it and drove it from louisville kentucky to Alabama about 400 miles no problems. At the time or purchase the guy said the light was on because it was throwing a code 90640 and it was the pcm that needed replacing....we had done this before so no problem.

Ok the next day after purchase we go to start it and it won't..not on the first try but by the 2nd or 3rd try it starts and starts fine until it stils for hours or over night..we still had not replaced the computer and we attributed it all to that.

now 1 year later it still starts the same no better no worse but we replaced the complete computer about 6 months ago but the engine light is still there and so is the problem..but it has never failed to start.


last today we took it to the shop to have to codes pulled and there was one for the quad control module and the guy said it was the ignition module...the code number was the same as the original one frm the guy we purchased it from..but it is not for pcm but for ignition..now we figure it's solved so we take the module off..take it to pep boys to have it tested and it was good Wh@t!!

anyway we do our own routine maintenance oil plugs wires etc the codes are listed below please help me with this problem..thanks

p0640
p0342
p0406

Here's what the codes listed mean:

P0640 <not listed as anODBII standard code>
P0342 Camshaft Position Sensor Circuit Low Input
P0406 Exhaust Gas Recirculation Sensor A Circuit High

It is interesting that you have a PCM (ODB four digit codes) instead of an ECM (two digit codes) in that year (94 Lesaber). Could relate to the mysterious unlisted 0640 code.

BTW: I occationally have this problem too on a 90 Lesaber and I am interested what it resoves to.