My (1988 XJ40 I6 3.6l) recently has been starting rough now it wasn't out of the ordinary for it to occasionally have meh starts but recently its been taking me 3 attempts to start my car (turn key br br br br unturn key not to flood give few seconds turn key repeat) it isn't my starter and it isn't a lack of power i unplug my battery at night due to previous issues with draws so im unsure as to what it is.

and today my car started up with only 2 attempts Yay right? No after it started it decided it wanted to become a tuned diesel and rev away to its hearts desire and to start Revving to 3500rpms and held for a few seconds only to drop to 1500rpms and idle at that speed until i started driving where it finally came back to its usual rpm idle of 750-900 rpms

any clue where is should start

(Thank-you for taking the time out of your day to read this and if you leave a comment trying to help double thank-you)

 

Start with simple things. Make sure your pump is running when you first turn the key. You should be able to just hear it in the left rear wheel well. Check your ignition system for wires arcing and check inside cap and rotor for decent condition. Check all your vacuum hoses. I use a can of brake cleaner while it's running, a change in idle when sprayed means a leak, but Be Careful to hit only the vacuum lines as much as possible. Do a search of this section of the forum to find many other suggestions, there is almost unlimited info here especially on no-start and rough idle problems. Mine start at the touch of the key, and they should idle very smoothly.