94 Shadow ES 3.0L Idle Problems

[Scholar79]

I have been trying to solve these problems on my 94 Shadow ES 3.0L 41TE for quite some time, but have come up with a loss. There are also no fault codes. The problems may be all related to one item as they appear to all
correspond to the car's idle. The car has less than 40,000 miles.
(1) Shaky/somewhat rough idle (hot or cold)
(2) After sitting for awhile, i.e. 2 hours, and the car is started, the idle goes up to 1500 like it should, but instantly drops way down to about 200 or so (car almost stalls), and thens goes back up to about 1000. What doesn't really make any sense is if the car sits OVERNIGHT it usually starts great in the morning; it is just long-delayed subsequent starts after that.
(3) Car's gas mileage is not like it should be. Only getting about 210 miles per tank.

Things done so far are as follows:

(1) Tune-up -- Air filter, fuel filter, plugs (Champions RN11YC @ .44in
gap), 7mm wires, PCV valve, rotor, and distributor cap.
(2) Throttle body cleaned.

If anyone can lead me in the right direction, it would be greatly appreciated.

TIA,

Matt

[vinbags44]

Hey Matt...did you check youre fuel pump or filter?? Vinnie..

[Scholar79]

I've replaced the fuel filter about a month ago. No change, though. The old one must've been the original because that thing did not want to come off. I sprayed MoPar Combustion Chamber cleaner into the car to see if that helped. So far, not a whole lotta difference. The only other thing I can think of is a burnt valve (although at 40000 miles?), or clogged fuel injector(s). I put some fuel injector cleaner into the tank, but that didn't do anything either. Ugh!